Admin: add 'show version' (#11079)

### What problem does this PR solve?

```
admin> show version;
show_version
+-----------------------+
| version               |
+-----------------------+
| v0.21.0-241-gc6cf58d5 |
+-----------------------+
admin> \q
Goodbye!

```

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

---------

Signed-off-by: Jin Hai <haijin.chn@gmail.com>

api/apps/auth/github.py

@@ -34,7 +34,7 @@ class GithubOAuthClient(OAuthClient):
 
     def fetch_user_info(self, access_token, **kwargs):
         """
-        Fetch github user info.
+        Fetch GitHub user info.
         """
         user_info = {}
         try:

api/apps/auth/oidc.py

@@ -43,7 +43,8 @@ class OIDCClient(OAuthClient):
         self.jwks_uri = config['jwks_uri']
 
 
-    def _load_oidc_metadata(self, issuer):
+    @staticmethod
+    def _load_oidc_metadata(issuer):
         """
         Load OIDC metadata from `/.well-known/openid-configuration`.
         """

api/apps/system_app.py

@@ -29,7 +29,7 @@ from api.utils.api_utils import (
     server_error_response,
     generate_confirmation_token,
 )
-from api.versions import get_ragflow_version
+from common.versions import get_ragflow_version
 from common.time_utils import current_timestamp, datetime_format
 from timeit import default_timer as timer