- Fixes parsing of private use tag (the full tag is considered as "private used" and not as "language"). - Validate properly private use tags (`x--` is not considered valid anymore).

Moves back Serde feature from `dep:serde` to `serde` (#10)

Moves back Serde feature from `dep:serde` to `serde` (#10)

`no_std` support and MSRV to 1.63