github CI: set PKG_CONFIG_PATH again

strange: on macOS, the globally set PKG_CONFIG_PATH was overwritten,
thus the borg build did not find openssl any more. setting it here
locally again works around the issue.

.github/workflows/ci.yml

@@ -117,10 +117,18 @@ jobs:
         python -m pip install --upgrade pip setuptools wheel
         pip install -r requirements.d/development.txt
     - name: Install borgbackup
+      env:
+        # we already have that in the global env, but something is broken and overwrites that.
+        # so, set it here, again.
+        PKG_CONFIG_PATH: "/usr/local/opt/openssl@1.1/lib/pkgconfig:$PKG_CONFIG_PATH"
       run: |
         # pip install -e .
         python setup.py -v develop
     - name: run tox env
+      env:
+        # we already have that in the global env, but something is broken and overwrites that.
+        # so, set it here, again.
+        PKG_CONFIG_PATH: "/usr/local/opt/openssl@1.1/lib/pkgconfig:$PKG_CONFIG_PATH"
       run: |
         # do not use fakeroot, but run as root. avoids the dreaded EISDIR sporadic failures. see #2482.
         #sudo -E bash -c "tox -e py"