🔧 Use ubuntu-latest in CI (#1439)

Ubuntu 20.04 is phased out.

Author: ubmarco

.github/workflows/ci.yaml

@@ -7,7 +7,7 @@ jobs:
 
   lint:
     name: Lint
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v4
     - name: Set up Python

.github/workflows/docs.yaml

@@ -5,7 +5,7 @@ on:
 jobs:
   linkcheck:
     name: Docs-Linkcheck
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
       - name: Set Up Python