Remove requirements.txt in favor of pure setup.cfg to let dependabot properly handle upgrades

Author: aiudirog

.github/workflows/ci.yml

@@ -45,7 +45,7 @@ jobs:
         run: |
           python -m pip install -U pip
           python -m pip install -U setuptools wheel
-          python -m pip install -U -r requirements.txt pytest-coverage codecov
+          python -m pip install -U .[all] pytest-cov codecov
       - name: Run Tests
         run: python -m pytest --cov=httpx_gssapi --cov-report=xml
       - name: Upload Coverage

requirements.txt

@@ -27,9 +27,13 @@ packages = httpx_gssapi
 install_requires =
     httpx>=0.16,<0.22
     gssapi
-tests_require =
+
+[options.extras_require]
+test =
     pytest
     k5test
+all =
+    %(test)s
 
 [options.package_data]
 * =