Remove workaround for older pillow in macOS CI

.github/workflows/ci.py

@@ -40,10 +40,7 @@ def install_deps():
     if is_bundle:
         install_bundle()
     else:
-        if is_macos:
-            # needed for zlib for pillow, should not be needed after pillow 8.0
-            os.environ['PKG_CONFIG_PATH'] = '/usr/local/opt/zlib/lib/pkgconfig'
-        cmd = 'pip3 install Pillow pygments'
+        cmd = 'python3 -m pip install Pillow pygments'
         if sys.version_info[:2] < (3, 7):
             cmd += ' importlib-resources dataclasses'
         run(cmd)