Bump MSRV

[tcharding]

• Patch 1 is prep, run the formatter.

• Patch 2 is:

  As we are doing ecosystem wide; bump the MSRV to Rust 1.48.0

  Includes:

  • A non-trivial clippy fix
  • Removal of the MacOS carve out in CI, no clue if this is fixed with Rust 1.48, we will see if ci is green.

[tcharding]

Put up as part of #92 to save rebase bother.