base_transactionStatus: consider removing Beta label

The base_transactionStatus method has been labeled Beta in the docs since it was introduced in v0.3.0. Looking at the recent PR #1222 that removed the Beta label from eth_subscribe, I wanted to check whether base_transactionStatus is now stable enough to have its Beta label removed as well.

It's been available across multiple releases now and the minimum client version requirement (v0.3.0) is well behind the current stable release. If it's considered stable, happy to open a PR to remove the label.