Update to winnow 0.7

[0e4ef622]

Tried to keep changes fairly minimal.

[0e4ef622]

Can we get either this PR or #127 merged and released? Currently I can't use this crate with anything that has a transitive dependency on winnow ^0.6.26 (like nrf-sdc) because cargo considers them to be conflicting.

error: failed to select a version for `winnow`.
    ... required by package `nrf-sdc-sys v0.2.0`
    ... which satisfies dependency `nrf-sdc-sys = "^0.2.0"` of package `nrf-sdc v0.3.0`
    ... which satisfies dependency `nrf-sdc = "^0.3.0"` of package `my-project v0.1.0`
versions that meet the requirements `^0.6.26` are: 0.6.26

all possible versions conflict with previously selected packages.

  previously selected package `winnow v0.6.24`
    ... which satisfies dependency `winnow = "=0.6.24"` of package `kdl v6.5.0`
    ... which satisfies dependency `kdl = "^6.5.0"` of package `memory-spec v0.1.0`
    ... which satisfies dependency `memory-spec = "^0.1.0"` of package `my-project v0.1.0`

failed to select a version for `winnow` which could resolve this conflict