Pin GHA runner versions (#28215)

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

.github/workflows/docs.yml

@@ -17,7 +17,7 @@ concurrency:
 jobs:
     build:
         name: GitHub Pages
-        runs-on: ubuntu-latest
+        runs-on: ubuntu-24.04
         steps:
             - name: Fetch element-desktop
               uses: actions/checkout@v4
@@ -99,7 +99,7 @@ jobs:
         environment:
             name: github-pages
             url: ${{ steps.deployment.outputs.page_url }}
-        runs-on: ubuntu-latest
+        runs-on: ubuntu-24.04
         needs: build
         steps:
             - name: Deploy to GitHub Pages