[ot] .github/workflows: bump release build to ubuntu-22.04

Required to get the necessary `glib` version required for QEMU (>=2.66.0).
Note that binaries build from `ubuntu-22.04` will no longer be usable
from `ubuntu-20.04` due to `glibc` incompatibility.

Author: jwnrt

.github/workflows/create_release.yml

@@ -15,7 +15,7 @@ jobs:
       BUILD_DIR: build
       BRANCH_NAME: ${{ github.event.repository.default_branch }}
       RELEASE_BIN_ARCHIVE: qemu-ot-earlgrey-${{ inputs.release_tag }}-x86_64-unknown-linux-gnu.tar.gz
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     timeout-minutes: 10
     steps:
       - name: Check out repository