CI: Use alpine:latest image for running

.gitlab-ci.yml

-image: alpine:3.10
+image: alpine:latest
 
 before_script:
   - apk add -q cppcheck build-base sdl2-dev sdl2_ttf-dev bash
@@ -15,7 +15,7 @@ static-analysis:
 clang-format:
   stage: check
   before_script:
-    - apk add -q clang git
+    - apk add -q clang-extra-tools git
   script:
     - test/clang-format.sh