[ fix ] Remove deprecated extra-source-files #27

Job	Run time
build-and-test (ubuntu-latest, Agda-2.7.0.1)	2m 0s
build-and-test (ubuntu-latest, Agda-2.7.0.1)	32m 51s
build-and-test (ubuntu-latest, Agda-2.6.4.3)	2m 0s
build-and-test (ubuntu-latest, Agda-2.6.4.3)	34m 9s
build-and-test (ubuntu-latest, Agda-2.6.3)	1m 21s
build-and-test (ubuntu-latest, Agda-2.6.3)	34m 27s
build-and-test (macos-latest, Agda-2.7.0.1)	2m 42s
build-and-test (macos-latest, Agda-2.7.0.1)	11m 55s
build-and-test (macos-latest, Agda-2.6.4.3)	2m 50s
build-and-test (macos-latest, Agda-2.6.4.3)	34m 40s
build-and-test (macos-latest, Agda-2.6.3)	1s
build-and-test (macos-latest, Agda-2.6.3)	33m 54s
build-and-test (macos-13, Agda-2.7.0.1)	1m 50s
build-and-test (macos-13, Agda-2.7.0.1)	56m 45s
build-and-test (macos-13, Agda-2.6.4.3)	1m 52s
build-and-test (macos-13, Agda-2.6.4.3)	55m 17s
build-and-test (macos-13, Agda-2.6.3)	1m 47s
build-and-test (macos-13, Agda-2.6.3)	58m 45s
build-and-test (windows-latest, Agda-2.7.0.1)	2m 17s
build-and-test (windows-latest, Agda-2.7.0.1)	41m 30s
build-and-test (windows-latest, Agda-2.6.4.3)	2m 7s
build-and-test (windows-latest, Agda-2.6.4.3)	41m 21s
build-and-test (windows-latest, Agda-2.6.3)	2m 6s
build-and-test (windows-latest, Agda-2.6.3)	43m 37s
	8h 22m 4s

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