Remove handling for older pyuvdata versions in tests

[bhazelton]

Description

Strip out handling in tests for pyuvdata versions older than 2.2.8 (which we now require)

Motivation and Context

Types of changes

• [x] Other

Checklist:

For all pull requests:

• [x] I have read the contribution guide.
• [x] My code follows the code style of this project.

Other checklist:

• [x] All new and existing tests pass.

[codecov[bot]]

Codecov Report

Base: 99.48% // Head: 99.48% // No change to project coverage :thumbsup:

Coverage data is based on head (7563ed9) compared to base (254215d). Patch has no changes to coverable lines.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #414   +/-   ##
=======================================
  Coverage   99.48%   99.48%           
=======================================
  Files          12       12           
  Lines        2153     2153           
=======================================
  Hits         2142     2142           
  Misses         11       11           

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[bhazelton]

These changes are included in #416