refactor(ci): ♻️ refactor makefile and modify its usage on CI

.github/workflows/test.yml

@@ -10,7 +10,7 @@ jobs:
     strategy:
       fail-fast: true
       matrix:
-        docker_image: [alpine, debian]
+        base_docker_image: [alpine, debian]
 
     steps:
       - uses: actions/checkout@v2
@@ -27,7 +27,11 @@ jobs:
         working-directory: test/requirements
 
       - name: Build Docker web server image
-        run: make update-dependencies
+        run: make build-webserver
+
+      - name: Build Docker nginx proxy test image
+        run: make build-nginx-proxy-test-${{ matrix.base_docker_image }}
 
       - name: Run tests
-        run: make test-${{ matrix.docker_image }}
+        run: pytest
+        working-directory: test