Fix permission error accessing /run/secrets (#10097)

Checks that the service has read access to the directory before trying
to read it

frigate/plus.py

@@ -37,8 +37,10 @@ class PlusApi:
         self.key = None
         if PLUS_ENV_VAR in os.environ:
             self.key = os.environ.get(PLUS_ENV_VAR)
-        elif os.path.isdir("/run/secrets") and PLUS_ENV_VAR in os.listdir(
-            "/run/secrets"
+        elif (
+            os.path.isdir("/run/secrets")
+            and os.access("/run/secrets", os.R_OK)
+            and PLUS_ENV_VAR in os.listdir("/run/secrets")
         ):
             self.key = Path(os.path.join("/run/secrets", PLUS_ENV_VAR)).read_text()
         # check for the addon options file