fix: compute az center correctly

[skhrg]

Bugfix on type 2/3 scans where the az center was computed wrong

Description

Compute az center with both endpoints instead of one

Motivation and Context

Without this you cannot run scans unless you pass an explicit az ref.

How Has This Been Tested?

Tested with scans last night

Types of changes

• 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)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.

[mhasself]

Whoops!