Move `Adapt` to a weak dependency #629

Job	Run time
test (1.0, ubuntu-latest, x64)	6m 30s
test (1.0, windows-latest, x64)	12m 50s
test (1.0, macOS-latest, x64)	6m 31s
test (1.6, ubuntu-latest, x64)	4m 45s
test (1.6, windows-latest, x64)	8m 28s
test (1.6, macOS-latest, x64)	6m 18s
test (1, ubuntu-latest, x64)	6m 4s
test (1, windows-latest, x64)	5m 43s
test (1, macOS-latest, x64)	6m 4s
test (~1.10.0-0, ubuntu-latest, x64)	4m 32s
test (~1.10.0-0, windows-latest, x64)	6m 9s
test (~1.10.0-0, macOS-latest, x64)	6m 53s
test (nightly, ubuntu-latest, x64)	4m 36s
test (nightly, windows-latest, x64)	7m 57s
test (nightly, macOS-latest, x64)	5m 55s
test (ubuntu-latest, 1, x86)	5m 25s
	1h 44m 40s

Provide feedback