Enforce toolchain requirement in generate.sh

[gmlewis]

@dnwe - does this seem like a reasonable change for the use of all developers in this repo?

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.26%. Comparing base (2b8c7fa) to head (94df24b).
Report is 220 commits behind head on master.

Additional details and impacted files

@@ Coverage Diff @@## master #3428 +/- ##
==========================================
- Coverage 97.72% 92.26% -5.46% 
==========================================
Files 153 174 +21 Lines 13390 15023 +1633 ==========================================
+ Hits 13085 13861 +776 - Misses 215 1068 +853 - Partials 90 94 +4 

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[dnwe]

@gmlewis seems reasonable — an alternative would be to set toolchain directives in the go.mod files to the latest 1.22.x as the 'auto' default will pick that up too

[gmlewis]

This seems like lower maintenance needed, so let's run with this for now.