Enable MIRI testing

[wcampbell0x2a]

To my understanding, miri doesn't really like some of bitvec's data structure. Before bitvec-v1.0.0 we tested this in CI as it worked! With the update to bitvec-v1.0.0 we commented that check out. This comment out was removed with the new CI: https://github.com/sharksforarms/deku/pull/390.

Anyway, if possible. enable this back on CI!

See:

• https://github.com/sharksforarms/deku/issues/266
• https://github.com/ferrilab/bitvec/issues/193
• (Should be fixed on the next release of bitvec) https://github.com/ferrilab/bitvec/issues/188