Tests

Add the modifies_memory macro (#1270) #3099

Job	Run time
check std	16s
clippy	1m 11s
check serde	18s
check no-default-features	26s
docs	1m 7s
fmt	13s
test stable --no-default-features	46s
test no_std	19s
test stable	1m 1s
test stable --all-features	1m 13s
test beta --no-default-features	54s
test beta	59s
test beta --all-features	1m 20s
test nightly --no-default-features	52s
test nightly	59s
test nightly --all-features	1m 27s
	13m 21s

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