Fix bug report templates

[codeguru42]

https://github.com/jruby/activerecord-jdbc-adapter no longer has a rails-5 branch

Closes #1382.

All Submissions:

• I've checked to ensure there aren't other open Pull Requests for the same update/change.
• I've submitted a ticket for my issue if one did not already exist.
• My submission passes all tests. (Please run the full test suite locally to cut down on noise from travis failures.)
• I've used Github auto-closing keywords in the commit message or the description.
• I've added/updated tests for this change.

Bug fixes and Changes to Core Features:

• I've included an explanation of what the changes do and why I'd like you to include them.
• I've provided test(s) that fails without the change.

Test Plan:

Reviewer Checklist:

• Maintains compliance with JSON:API
• Adequate test coverage exists to prevent regressions

[codeguru42]

@lgebhardt @dgeb Does this appear to be sufficient to fix the bug report template? Any suggestions of anything else to look at to change?

[bf4]

I think per https://github.com/jruby/activerecord-jdbc-adapter the correct approach would be branch 50-stable