Add Execa to list of users (#1435)

README.md

@@ -637,6 +637,7 @@ We collect a list of common workarounds for various websites in our [troubleshoo
 - https://github.com/analysis-tools-dev/dynamic-analysis
 - https://github.com/mre/idiomatic-rust
 - https://github.com/bencherdev/bencher
+- https://github.com/sindresorhus/execa
 - https://github.com/lycheeverse/lychee (yes, the lychee docs are checked with lychee 🤯)
 
 If you are using lychee for your project, **please add it here**.