[CI] Unbreak testing flow

The images removed/are in the process of removing compose v1.

This also pins to an actual version instead of always using latest. Seems like a smart thing to do.

https://github.com/actions/runner-images/issues/9557

.github/prepare-docker-image/action.yml

@@ -15,5 +15,5 @@ runs:
         tags: e621
 
     - name: Set docker run command
-      run: echo "DOCKER_RUN=docker-compose run -e CI=true" >> "$GITHUB_ENV"
+      run: echo "DOCKER_RUN=docker compose run -e CI=true" >> "$GITHUB_ENV"
       shell: bash

.github/workflows/checks.yml

@@ -13,7 +13,7 @@ permissions:
 
 jobs:
   docker-build:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
 
     steps:
       - name: Set up Docker Buildx
@@ -27,7 +27,7 @@ jobs:
           tags: e621
 
   rubocop:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
     needs: docker-build
 
     steps:
@@ -38,7 +38,7 @@ jobs:
         run: $DOCKER_RUN rubocop --format github
 
   tests:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
     needs: docker-build
 
     steps: