Fix CI Failures (#472)

* bump-python-on-CI

* fix-lint

* use-ubuntu-latest

Author: Darshan808

.github/workflows/codeql-analysis.yml

@@ -20,7 +20,7 @@ permissions:
 jobs:
   analyze:
     name: Analyze
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
 
     strategy:
       fail-fast: false

.github/workflows/fix-license-header.yml

@@ -5,7 +5,7 @@ on:
 
 jobs:
   header-license-fix:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
 
     permissions:
       contents: write

.github/workflows/tests.yml

@@ -19,7 +19,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, windows-latest, macos-latest]
-        python-version: ["3.8", "3.12"]
+        python-version: ["3.9", "3.12"]
         include:
           - os: windows-latest
             python-version: "3.9"

jupyterlab_server/handlers.py

@@ -170,7 +170,7 @@ def get(
         page_config["treePath"] = tree_path
 
         # Write the template with the config.
-        tpl = self.render_template("index.html", page_config=page_config)  # type:ignore[no-untyped-call]
+        tpl = self.render_template("index.html", page_config=page_config)
         self.write(tpl)