Update Actions to test Bashbrew the same way we run it everywhere now

Also, explicitly test both Dockerfiles.

Author: tianon

.github/workflows/ci.yml

@@ -18,18 +18,25 @@ jobs:
       - uses: actions/checkout@v2
       - name: Build
         run: |
-          docker build --tag bashbrew --pull .
-          docker run --rm bashbrew tar -cC /usr/local/bin bashbrew | tar -xv
-          ./bashbrew --version
+          ./bashbrew.sh --version > /dev/null
+          bin/bashbrew --version
       - name: Smoke Test
         run: |
           image='https://github.com/docker-library/official-images/raw/master/library/hello-world'
-          ./bashbrew list "$image"
-          ./bashbrew list --uniq "$image"
-          ./bashbrew cat "$image"
-          ./bashbrew from --uniq "$image"
-  release:
-    name: Release (test)
+          bin/bashbrew list "$image"
+          bin/bashbrew list --uniq "$image"
+          bin/bashbrew cat "$image"
+          bin/bashbrew from --uniq "$image"
+  dockerfile:
+    name: Test Dockerfile
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Build Dockerfile
+        run: |
+          docker build --pull .
+  dockerfile-release:
+    name: Test Dockerfile.release
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2