Pin to Ubuntu 22 (#145)

Ubuntu 24 seems to have slightly different kerning / aliasing so we'll
need to update all out screenshots. In the meantime, pin to 22.

.github/workflows/end-to-end-tests.yaml

@@ -45,7 +45,7 @@ env:
 jobs:
     build:
         name: "Build Element-Web"
-        runs-on: ubuntu-latest
+        runs-on: ubuntu-22.04
         if: inputs.skip != true
         steps:
             - name: Checkout code
@@ -95,7 +95,7 @@ jobs:
         name: "Run Tests ${{ matrix.runner }}/${{ strategy.job-total }}"
         needs: build
         if: inputs.skip != true
-        runs-on: ubuntu-latest
+        runs-on: ubuntu-22.04
         permissions:
             actions: read
             issues: read
@@ -162,7 +162,7 @@ jobs:
         name: end-to-end-tests
         needs: playwright
         if: always()
-        runs-on: ubuntu-latest
+        runs-on: ubuntu-22.04
         steps:
             - uses: actions/checkout@v4
               if: inputs.skip != true