Mention that 'pyenv update' is also required now

Author: jankeromnes

README.md

@@ -79,7 +79,7 @@ OPTIONS:
 
 Tier 0 (default - no rework needed):
 - [x] Remove trailing whitespace (uses `git`, `xargs` and `sed`)
-- [x] Update pinned pyenv tool versions in Dockerfiles (requires `pyenv`)
+- [x] Update pinned pyenv tool versions in Dockerfiles (requires `pyenv` and `pyenv update`)
 - [x] Update pinned nvm tool versions in Dockerfiles (requires `nvm`)
 - [x] Update pinned sdkman tool versions in Dockerfiles (requires [sdkman](https://github.com/sdkman/sdkman-cli))
 - [x] Update pinned rr versions in Dockerfiles