Update and simplify the CI workflow

[cuviper]

• Update to actions/checkout@v3
• Switch from actions-rs/toolchain to dtolnay/rust-toolchain
• Switch from actions-rs/cargo to plain run
• Stop explicitly naming CI steps
• Add 1.60.0 to the test matrix

[cuviper]

bors r+

[bors[bot]]

Build succeeded:

• Format
• Missing Target
• No Std
• Test (1.0.0)
• Test (1.10.0)
• Test (1.15.0)
• Test (1.20.0)
• Test (1.25.0)
• Test (1.30.0)
• Test (1.35.0)
• Test (1.40.0)
• Test (1.45.0)
• Test (1.5.0)
• Test (1.50.0)
• Test (1.55.0)
• Test (1.60.0)
• Test (beta)
• Test (nightly)
• Test (stable)