Update bson-ruby.yml workflow

[MSP-Greg]

Updates the main CI file bson-ruby.yml

1. Add workflow_dispatch - this is used in other workflows here. It allows maintainers to force a CI run. It also does the same for users with forks of this repo. Helpful for when changes to dependencies (or Ruby) happen that may affect this.

2. Update actions/checkout to actions/checkout@v4. Used in other workflows

3. Add quotes to 3.0. Actions' yaml parser truncates decimal zeros. So, unquoted 3.0 will specify 3, and unquoted 3.10 will specify 3.1. See recent workflow.

4. WIndows - use ucrt instead of mingw. Ruby 3.0 was the last publicly available mingw build. Or, Ruby 3.5 will be released as a ucrt build. Hence, better to test with a Ruby head ucrt.

5. There are quite a few items installed via bundler, use caching.