fix(cmake): change find_package to find_dependency for slick-net #25

Job	Run time
build-and-test (windows-latest, Release)	7m 8s
build-and-test (macos-latest, Release)	2m 55s
build-and-test (ubuntu-latest, Release)	3m 28s
build-and-test (macos-latest, Debug)	3m 27s
build-and-test (windows-latest, Debug)	5m 12s
build-and-test (ubuntu-latest, Debug)	2m 43s
	24m 53s

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