also ensure that `done()` is called on all mocks (otherwise the tests
now fail). this also unearthed 1-2 bugs where the expectations were
wrong.

since e-h-m 0.10.0 requires rust 1.63 the MSRV for this crate has been
raised accordingly as we now cannot test on older releases anymore. it
might still work there however.

as alpha.10 of embedded-hal has added `SetDutyCycle` as the equivalent /
successor of the old `PwmPin` support for it can now be added here.

since e-h 1.0.0 will be released at the end of this year it's safe to
just directly migrate to the RC1 instead of adding it as an optional
support (requiring another breaking change in a later step which would
then remove e-h 0.2 support).

a new warning was caused by the `?` operator as it contains
`#[allow(unreachable_code)]`, which clashes with the previous `forbid`
rule.

as `forbid` does not allow `deny` to override it this would cause a
compile error, however due to a compiler bug this was previously not
reported at all and has now been changed to a warning in a recent(-ish)
version of rustc and will eventually become a compile error.

with `deny` it's still possible to use `allow`, thus there's no warning

see also rust-lang/rust#76053

thanks @jannic