Try to fix uvloop build errors on macos-latest (2)

.github/workflows/tests.yml

@@ -92,18 +92,10 @@ jobs:
           path: .venv
           key: venv-${{ matrix.os }}-${{ matrix.python-version }}-${{ hashFiles('**/poetry.lock') }}-${{ secrets.CACHE_VERSION }}
 
-      - name: Apply macos-specific workarounds when building uvloop on PyPy
-        if: >
-          matrix.os == 'macos-latest'
-          && startswith(matrix.python-version, 'pypy')
-          && steps.cached-poetry-dependencies.outputs.cache-hit != 'true'
-        run: |
-          set -eu
-          pip install -U pip
-
       - name: Project dependencies
         if: steps.cached-poetry-dependencies.outputs.cache-hit != 'true'
         run: |
+          export CFLAGS="$CFLAGS -std=c11"
           poetry install --no-interaction -E fast -E redis -E proxy -E i18n -E docs
 
       - name: Lint code