Constrain timezone parsing

[jtmoon79]

Constrain timezone parsing further. Only allow optional colon char ":" between timezone hour offset and timezone minute offset. Previously these patterns were optionally allowed: ":", ": ", " :", " : ", " ".

Issue #660

Follow-up to discussion #807 (comment)

[jtmoon79]

The commit cargo fmt updates is separate from the initial commit Constrain timezone parsing. This allows easier distinction of significant changes for this PR.

The cargo fmt command affected many lines, including some not related to the significant change.

[jtmoon79]

The last Action had one Job failure for rust_msrv (ubuntu-latest)

Run cargo test --lib --features unstable-locales,wasmbind,clock,serde,windows-sys --color=always -- --color=always
    Updating crates.io index
 Downloading crates ...
  Downloaded num-traits v0.2.15
  Downloaded iana-time-zone v0.1.54
  Downloaded itoa v1.0.6
  Downloaded doc-comment v0.3.3
  Downloaded quote v1.0.26
  Downloaded pure-rust-locales v0.5.6
  Downloaded serde v1.0.158
  Downloaded ryu v1.0.13
  Downloaded num-iter v0.1.43
  Downloaded autocfg v1.1.0
  Downloaded bincode v1.3.3
  Downloaded proc-macro2 v1.0.53
  Downloaded num-integer v0.1.45
  Downloaded syn v2.0.9
error: failed to parse manifest at `/home/runner/.cargo/registry/src/github.com-1ecc6299db9ec823/syn-2.0.9/Cargo.toml`

Caused by:
  failed to parse the `edition` key

Caused by:
  this version of Cargo is older than the `2021` edition, and only supports `2015` and `2018` editions.
Error: Process completed with exit code 101.

I think that fix should be a separate PR. But I can fix it in this PR teh maintainers prefer that.

[djc]

Thanks!