CI: fix up things #3

Job	Run time
Julia nightly - ubuntu-latest - x64	3m 35s
Julia 1 - macos-latest - x64	19m 23s
Julia 1 - ubuntu-latest - x64	16m 5s
Test with `JETLS_DEV_MODE = true`	12m 12s
Julia 1.12 - ubuntu-latest - x64	12m 18s
Test with `JULIA_NUM_THREADS = 4,2`	12m 7s
Test with `JETLS_DEBUG_LOWERING = true`	11m 57s
Test jetls executable	6m 3s
	1h 33m 40s

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