Fix artifact upload patterns.

actions/glob doesn't appear to support |.

See https://github.com/actions/toolkit/tree/main/packages/glob#glob-behavior

Author: Julian

.github/workflows/ci.yml

@@ -12,5 +12,6 @@ jobs:
       - uses: actions/upload-artifact@v2
         with:
           path: |
-              *.(html|txt)
+              *.html
+              *.txt
               !requirements.txt