clippy: actually fail if there are any warnings
So far, only errors would trip the CI, this makes it so all warnings are
elevated to errors, making it a CI fail if any warnings are present.
This was the intended behavior, I just missed this when adding clippy.
# See http://EditorConfig.org for the specification
root = true
[*.py]
indent_size = 4
indent_style = space
trim_trailing_whitespace = true
end_of_line = lf
[*.{c,h}]
indent_size = 8
indent_style = tab
trim_trailing_whitespace = true
end_of_line = lf
[*.t]
indent_size = 2
indent_style = space
trim_trailing_whitespace = false
end_of_line = lf