Update all GitHub actions workflows to Ubuntu latest

AA-Turner · AA-Turner · commit b58eb61c9f5d · 2022-10-14T16:04:04.000+01:00
diff --git a/.github/workflows/latex.yml b/.github/workflows/latex.yml
@@ -7,7 +7,7 @@ permissions:
 
 jobs:
   test:
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-latest
     name: Test on LaTeX image
     container:
       image: ghcr.io/sphinx-doc/sphinx-ci
diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
@@ -7,7 +7,7 @@ permissions:
 
 jobs:
   ubuntu:
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-latest
     name: Python ${{ matrix.python }} (${{ matrix.docutils }})
     strategy:
       fail-fast: false
