ci: must install docker explicitly and /var/run is in /run on alpine

.gitea/workflows/test-alpine.yaml

@@ -12,15 +12,7 @@ jobs:
       - name: List available binaries
         run: ls -lah /bin /sbin /usr/bin /usr/sbin /usr/local/bin
       - name: List available sockets
-        run: ls -lah /var/run
+        run: ls -lah /var/run /run
-
-  try-docker:
-    runs-on: alpine-latest
-    steps:
-      - name: Try listing containers
-        run: docker ps
-      - name: Try running something
-        run: docker run -i --rm alpine:latest echo running inside alpine
 
   try-docker-with-install:
     runs-on: alpine-latest