Don't run CodSpeed on merge_group events #1026

Job	Run time
Build docs & run doctests	19s
Verify dev env (ubuntu-latest)	31s
Run CodSpeed benchmarks	1m 54s
Verify dev env (windows-latest)	42s
Check types using pyright	15s
Tests & Mypy on 3.7	53s
Tests & Mypy on 3.8	37s
Tests & Mypy on 3.9	53s
Tests & Mypy on 3.10	1m 6s
Tests & Mypy on 3.11	54s
Tests & Mypy on 3.12	1m 25s
Tests & Mypy on 3.13	47s
Tests & Mypy on pypy-3.8	55s
Tests & Mypy on pypy-3.9	43s
Tests & Mypy on pypy-3.10	53s
Combine & check coverage.	8s
required-checks-pass	2s
	12m 57s

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