Refined-github: "Quick PR Buttons" doesn't appear in certain occasions

[tallen1983]

UPDATE: It is not specific to Octotree, that is just one way to show the issue. See @busches's informative comment below.

When using Octotree, there is a way you can navigate to the Files Changed tab where the Refined GitHub extensions (at least the Comment/Approve/Request Changes buttons) do not get applied.

Steps to reproduce:

1. Install Octotree
2. When on a PR, go to the Conversation tab.
3. Expand the Octotree column.
4. Click on one of the changed files in the Octotree column
5. It will move to the Files Changed tab, with the requested file shown.
6. Click the Review Changes button
7. Notice we have the old god-awful radio buttons instead of the much easier to use buttons

[busches]

I don't believe this is specific to Octotree.

1. Open a PR
2. Click Commits
3. Click a Commit
4. Click Review changes
5. Notice the radio buttons, e.g. 8dce75db4fd9d30a5aff460f62b83d0032c67fd6

Root cause is our regex is too specific /^pull\/\d+\/files/ and doesn't match other pages with Review options.