Q1'21 handler maintenance

[calebhailey]

Repository Updates

• Review any outstanding PRs/issues (are any easily addressable as part of this work?)
• Switch default branch from master to main (ref https://github.com/github/renaming)

Module Updates

• Update SDK, core, and all other modules with 'go get -u' (note: This may require some manual cleanup)
• Cleanup with 'go mod tidy'

README Updates

• Add note on templates and link to docs, when needed
• Ensure help output is current
• Caveat on using check annotations (ref https://github.com/sensu/sensu-pagerduty-handler/blob/master/README.md)
• Make sure annotations are explained as overrides
• Add table of environment variables available
• Make sure layout matches current standard
• Remove empty sections (e.g. Files, Additional Notes)

Golang version updates

• Update go.mod to use 1.14
• Update GitHub Actions (release and test) to use 1.14

GitHub Actions Updates

• All have lint, test, and release actions
• Add PR to lint and test actions on OSS handlers

Secrets update

• For any password/token arguments, ensure 'Secret: true' is set

Code updates

• Output supporting templates where it makes sense to (make sure to document in README)
• Replace import of types with api/core/v2 and change *types.Event references to *corev2.Event
• Run 'gofmt' on all source files

Output logging

• Output logging information (e.g. any incident or job # created)

Release

• Make sure Bonsai and GoReleaser configs are in sync and functioning Remove 32 bit macOS from Bonsai
• Add any changes to CHANGELOG
• Submit PR
• After merge, cut a new release
• In bonsai make sure the handler has the right tier (supported, enterprise)

Update curation(s)

• Update (or add new) curations to use new version/assets (add in template args if available)