Updated Workflow to read from the head instead as checking against main on merge will always result in nothing

[SteveMcGrath]

Description

Updated Deployment pipeline connector matrix creation in order to correct for how the matrix is computed. The previous
approach works on PRs as the comparison is against main. However the deployment pipeline must compare against the
prior commit in the HEAD as the PR changes have already been merged in.

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Tested locally with act

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules