OpenAPI: Make extension optional

Install with: pip install 'responder[openapi]'

.github/workflows/test.yaml

@@ -12,8 +12,9 @@ concurrency:
   cancel-in-progress: true
 
 jobs:
-  test:
-    name: "Python ${{ matrix.python-version }} on ${{ matrix.os }}"
+
+  test-full:
+    name: "Full: Python ${{ matrix.python-version }} on ${{ matrix.os }}"
     runs-on: ${{ matrix.os }}
     strategy:
       fail-fast: false
@@ -65,11 +66,33 @@ jobs:
     - name: Install package and run software tests (Python 3.6)
       if: matrix.python-version == '3.6'
       run: |
-        pip install '.[graphql,develop,test]'
+        pip install '.[full,develop,test]'
         poe test
 
     - name: Install and completely validate package (Python >=3.6)
       if: matrix.python-version != '3.6'
       run: |
-        uv pip install '.[graphql,develop,test]' --system
+        uv pip install '.[full,develop,test]' --system
+        poe check
+
+
+  test-minimal:
+    name: "Minimal: Python ${{ matrix.python-version }} on ${{ matrix.os }}"
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os: ["ubuntu-latest"]
+        python-version: ["3.13"]
+
+    steps:
+    - uses: actions/checkout@v4
+    - uses: actions/setup-python@v5
+      with:
+        python-version: ${{ matrix.python-version }}
+    - uses: yezz123/setup-uv@v4
+
+    - name: Install and completely validate package
+      run: |
+        uv pip install '.[develop,test]' --system
         poe check