ci: use ubuntu-22.04 on doc build (#549)

* ci: use ubuntu-22.04 on doc build

* ci: update nightly workflow

Author: RobPasMue

.github/workflows/ci_cd.yml

@@ -33,7 +33,7 @@ jobs:
 
   doc-build:
     name: "Build project documentation"
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
     steps:
       - name: Setup headless display
         uses: pyvista/setup-headless-display-action@v3

.github/workflows/nightly-build.yml

@@ -11,7 +11,7 @@ env:
 jobs:
   nightly-docs:
     name: Nightly documentation
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
     steps:
       - name: Setup headless display
         uses: pyvista/setup-headless-display-action@v3