Access certificates periodically

Tentatively closes #1965

qt/aqt/main.py

@@ -1370,6 +1370,7 @@ title="{}" {}>{}</button>""".format(
             True,
             parent=self,
         )
+        self.progress.timer(12 * 60 * 1000, self.refresh_certs, False, parent=self)
 
     def onRefreshTimer(self) -> None:
         if self.state == "deckBrowser":
@@ -1385,6 +1386,15 @@ title="{}" {}>{}</button>""".format(
         if elap > minutes * 60:
             self.maybe_auto_sync_media()
 
+    def refresh_certs(self) -> None:
+        # The requests library copies the certs into a temporary folder on startup,
+        # and chokes when the file is later missing due to temp file cleaners.
+        # Work around the issue by accessing them once every 12 hours.
+        import certifi
+
+        with open(certifi.where(), "rb") as f:
+            f.read()
+
     # Backups
     ##########################################################################
 

qt/mypy.ini

@@ -63,6 +63,8 @@ ignore_missing_imports = True
 ignore_missing_imports = True
 [mypy-stringcase]
 ignore_missing_imports = True
+[mypy-certifi]
+ignore_missing_imports = True
 
 [mypy-aqt.forms.*]
 disallow_untyped_defs = false