tailwind-merge 1.9.1

Fix arbitrary floats not supported in opacity, scale, etc. by @dcastil in https://github.com/dcastil/tailwind-merge/pull/196
- Up until now classes like opacity-50 opacity-[.025] weren't merged correctly. You might not have noticed since classes with arbitrary values are defined after the default ones in the output stylesheet, but merging it the other way around (opacity-[.025] opacity-50) would have led to a styling bug.
- This fix led to a new validator isNumber.
Fix arbitrary border color value being merged incorrectly by @dcastil in https://github.com/dcastil/tailwind-merge/pull/195

Full Changelog: https://github.com/dcastil/tailwind-merge/compare/v1.9.0...v1.9.1