test-check-rust-format: specify --edition=2018
rustfmt doesn't read Cargo.toml unless it's executed by cargo.
https://github.com/rust-lang/rustfmt#rusts-editions
# See http://EditorConfig.org for the specification
root = true
[*.py]
indent_size = 4
indent_style = space
trim_trailing_whitespace = true
[*.{c,h}]
indent_size = 8
indent_style = tab
trim_trailing_whitespace = true
[*.t]
indent_size = 2
indent_style = space
trim_trailing_whitespace = false