Wasm32-unknown-unknown tests not running

[Kody Musick]

I believe #677 broke wasm32-unknown-unknown testing by changing from:

target_arch = "wasm32"

to:

target = "wasm32-unknown-unknown"

Previous CI output has working tests:

...
test uuid::tests::test_iterbytes_impl_for_uuid ... ok
test uuid::tests::test_bytes_le_roundtrip ... ok
...

Current CI output has the following output:

Running unittests src/lib.rs (target/wasm32-unknown-unknown/debug/deps/uuid-a93fe0cd9dde70d6.wasm)
no tests to run!
     Running tests/macros.rs (target/wasm32-unknown-unknown/debug/deps/macros-6a1194c5d8da492d.wasm)
                                                  
no tests to run!