Use Rust 1.48.0 for `rustfmt`, `clippy`, and `tarpaulin` jobs.
Use Rust 1.48.0 for `rustfmt`, `clippy`, and `tarpaulin` jobs.

Additionally, disable osx and windows builds as well as combine
`rustfmt` and `clippy` jobs for build performance reasons. #223

iliekturtles/uom