Increase the max theme version

[davidfischer]

This increases the minor version of the default theme version.

• The big difference between 0.3.x theme versions and 0.4.x theme versions is that the CSS/JS is bundled with the theme in 0.4.x rather than relying on a single centralized version when built on Read the Docs (building locally is different). Not bundling resulted in version mismatches.
• This should go out after Decouple the theme JS from readthedocs.org #3968

[ericholscher]

👍

[ericholscher]

We need to fix the test that is checking for the specific version output.

[davidfischer]

Correct. That's sort of a weird test but I'll get it resolved. I figure some people are pinned to the latest theme and if there are any issues (we haven't seen any) they'll report it. This can go out in a release next week sometime.