Fix gdc-12 build #257

Job	Run time
Run all tests (dmd-latest, dmd, ubuntu-22.04, make)	2m 31s
Run all tests (dmd-latest, dmd, ubuntu-22.04, dub, min libdparse)	2m 44s
Run all tests (dmd-latest, dmd, macos-latest, make)	2m 29s
Run all tests (dmd-latest, dmd, macos-latest, dub, min libdparse)	3m 3s
Run all tests (dmd-latest, dmd, windows-latest, make)	5m 10s
Run all tests (dmd-latest, dmd, windows-latest, dub, min libdparse)	3m 40s
Run all tests (ldc-latest, ldmd2, ubuntu-22.04, make)	2m 58s
Run all tests (ldc-latest, ldmd2, ubuntu-22.04, dub, min libdparse)	3m 21s
Run all tests (ldc-latest, ldmd2, macos-latest, make)	4m 30s
Run all tests (ldc-latest, ldmd2, macos-latest, dub, min libdparse)	4m 3s
Run all tests (ldc-latest, ldmd2, windows-latest, make)	13m 15s
Run all tests (ldc-latest, ldmd2, windows-latest, dub, min libdparse)	5m 24s
Run all tests (dmd-latest, gdc-12, ubuntu-22.04, make)	5m 4s
	58m 12s

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