fix issues w/ python 3.8 typing

ChangeLog

@@ -1,6 +1,11 @@
 CHANGES
 =======
 
+* rtd
+* rtd
+* rtd
+* typo
+* rtd updates
 * remove old python versions
 * try to fix docs theme
 * try to fix docs theme

cfitall/providers/filesystem.py

@@ -21,7 +21,7 @@ class FilesystemProvider(ConfigProviderBase):
     prefix: str
 
     def __init__(
-        self, path: list[str], prefix: str, provider_name: str = "filesystem"
+        self, path: List[str], prefix: str, provider_name: str = "filesystem"
     ) -> None:
         """
         FilesystemProvider attempts to read json or yaml configuration files

cfitall/registry.py

@@ -72,7 +72,7 @@ def all(self) -> Dict:
         return values
 
     @property
-    def config_keys(self) -> list[str]:
+    def config_keys(self) -> List[str]:
         """
         Returns a list of currently used configuration keys as dotted paths, for
         use with the get() or set() methods.
@@ -88,7 +88,7 @@ def dict(self) -> Dict:
         return self._merge_configs()
 
     @property
-    def env_vars(self) -> list[str]:
+    def env_vars(self) -> List[str]:
         """
         Returns a list of environment variables known from config files and defaults
         """