[fix] pyright repported errors

The errors make pyright usage useless since a new error won't be seen [1].

[1] https://github.com/searxng/searxng/pull/1569

```
  searx/compat.py:11:27 - error: Expression of type "Type[cached_property[_T@cached_property]]" cannot be assigned to declared type "Type[cached_property]"
    "Type[cached_property[_T@cached_property]]" is incompatible with "Type[cached_property]"
    Type "Type[cached_property[_T@cached_property]]" cannot be assigned to type "Type[cached_property]" (reportGeneralTypeIssues)
  searx/utils.py:69:36 - error: Expression of type "None" cannot be assigned to parameter of type "str"
    Type "None" cannot be assigned to type "str" (reportGeneralTypeIssues)
  searx/utils.py:573:85 - error: Expression of type "None" cannot be assigned to parameter of type "int"
    Type "None" cannot be assigned to type "int" (reportGeneralTypeIssues)
  searx/webapp.py:1306:22 - error: Argument of type "str" cannot be assigned to parameter "__a" of type "BytesPath" in function "join"
    Type "str" cannot be assigned to type "BytesPath"
      "str" is incompatible with "bytes"
      "str" is incompatible with protocol "PathLike[bytes]"
        "__fspath__" is not present (reportGeneralTypeIssues)
  searx/webapp.py:1306:68 - error: Argument of type "Literal['themes']" cannot be assigned to parameter "paths" of type "BytesPath" in function "join"
    Type "Literal['themes']" cannot be assigned to type "BytesPath"
      "Literal['themes']" is incompatible with "bytes"
      "Literal['themes']" is incompatible with protocol "PathLike[bytes]"
        "__fspath__" is not present (reportGeneralTypeIssues)
  searx/webapp.py:1306:78 - error: Argument of type "str | Any | None" cannot be assigned to parameter "paths" of type "BytesPath" in function "join"
    Type "str | Any | None" cannot be assigned to type "BytesPath"
      Type "str" cannot be assigned to type "BytesPath"
        "str" is incompatible with "bytes"
        "str" is incompatible with protocol "PathLike[bytes]"
          "__fspath__" is not present (reportGeneralTypeIssues)
  searx/webapp.py:1306:85 - error: Argument of type "Literal['img']" cannot be assigned to parameter "paths" of type "BytesPath" in function "join"
    Type "Literal['img']" cannot be assigned to type "BytesPath"
      "Literal['img']" is incompatible with "bytes"
      "Literal['img']" is incompatible with protocol "PathLike[bytes]"
        "__fspath__" is not present (reportGeneralTypeIssues)
  searx/engines/mongodb.py:8:6 - warning: Import "pymongo" could not be resolved (reportMissingImports)
  searx/engines/mysql_server.py:9:8 - warning: Import "mysql.connector" could not be resolved (reportMissingImports)
  searx/engines/postgresql.py:9:8 - warning: Import "psycopg2" could not be resolved from source (reportMissingModuleSource)
  searx/engines/xpath.py:187:28 - warning: "categories" is not defined (reportUndefinedVariable)
  searx/search/__init__.py:184:82 - warning: "flask" is not defined (reportUndefinedVariable)
  searx/search/checker/background.py:19:26 - error: Type of "schedule" is partially unknown
    Type of "schedule" is "(delay: Any, func: Any, *args: Any) -> Literal[True]" (reportUnknownVariableType)
  searx/shared/__init__.py:8:12 - warning: Import "uwsgi" could not be resolved (reportMissingImports)
  searx/shared/shared_uwsgi.py:5:8 - warning: Import "uwsgi" could not be resolved (reportMissingImports)
```

2 files changed, 4 insertions, 3 deletions

diff --git a/searx/search/__init__.py b/searx/search/__init__.py
index c517814d..9d337916 100644
--- a/searx/search/__init__.py
+++ b/searx/search/__init__.py
@@ -2,11 +2,12 @@
 # lint: pylint
 # pylint: disable=missing-module-docstring, too-few-public-methods
 
-import typing
 import threading
 from timeit import default_timer
 from uuid import uuid4
 
+import flask
+
 from searx import settings
 from searx.answerers import ask
 from searx.external_bang import get_bang_url
@@ -181,7 +182,7 @@ class SearchWithPlugins(Search):
 
     __slots__ = 'ordered_plugin_list', 'request'
 
-    def __init__(self, search_query: SearchQuery, ordered_plugin_list, request: "flask.Request"):
+    def __init__(self, search_query: SearchQuery, ordered_plugin_list, request: flask.Request):
         super().__init__(search_query)
         self.ordered_plugin_list = ordered_plugin_list
         self.result_container.on_result = self._on_result
diff --git a/searx/search/checker/background.py b/searx/search/checker/background.py
index f47e7d75..f8dfed4f 100644
--- a/searx/search/checker/background.py
+++ b/searx/search/checker/background.py
@@ -16,7 +16,7 @@ from searx import logger, settings, searx_debug
 from searx.exceptions import SearxSettingsException
 from searx.search.processors import PROCESSORS
 from searx.search.checker import Checker
-from searx.shared import schedule, storage
+from searx.shared import schedule, storage  # pyright: ignore
 
 
 CHECKER_RESULT = 'CHECKER_RESULT'