Don't ship pyodbc on macOS as SQLServer integration is not shipped on macOS

[arbll]

What does this PR do?

Avoid trying to install pyodbc on darwin.

Motivation

It fails on darwin since no pre-built wheels are available for our builder os version.

Review checklist (to be filled by reviewers)

• PR title must be written as a CHANGELOG entry (see why)
• Files changes must correspond to the primary purpose of the PR as described in the title (small unrelated changes should have their own PR)
• PR must have changelog/ and integration/ labels attached
• Feature or bugfix must have tests
• Git history must be clean
• If PR adds a configuration option, it must be added to the configuration file.

[codecov]

Codecov Report

Merging #3461 into master will decrease coverage by 4.77%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #3461      +/-   ##
==========================================
- Coverage   86.29%   81.51%   -4.78%     
==========================================
  Files         740       69     -671     
  Lines       38558     5427   -33131     
  Branches     4585      688    -3897     
==========================================
- Hits        33272     4424   -28848     
+ Misses       4018      834    -3184     
+ Partials     1268      169    -1099

[zippolyte]

Need to add that to the agent requirements in datadog_checks_base as well. A ddev dep freeze should do that for you.