Add notify_start as dependency to build matrix job

[brandongregoryscott]

Add needs step to build to ensure slack notification starts before build jobs

Resolves #168 Github Actions: Update build job to depend on notify_start

• [x] Related GitHub issue(s) linked in PR description
• [x] Destination branch merged, built and tested with your changes
• [x] Code formatted and follows best practices and patterns
• [x] Code builds cleanly (no additional warnings or errors)
• [-] Manually tested
• [-] Automated tests are passing
• [-] No decreases in automated test coverage
• [-] Documentation updated (readme, docs, comments, etc.)
• [-] Localization: No hard-coded error messages in code files (minimally in string constants)