Two GitHub APIs don't return `patch` field when `per_page` argument exceeds 70

The GitHub rest api `get-a-commit` [1] and `list-pull-requests-files` [2] don't return the `patch` field when the `per_page` argument exceeds 70.

The original issue is SKARA-1332 [3]. And a detailed analysis is at
PR-1302 [4].

[1] https://docs.github.com/en/rest/commits/commits#get-a-commit
[2] https://docs.github.com/en/rest/pulls/pulls#list-pull-requests-files
[3] https://bugs.openjdk.java.net/browse/SKARA-1332
[4] https://github.com/openjdk/skara/pull/1302#issue-1211945938