Cryptocurrencies are generally open-source projects, so we can all take part in and monitor the ongoing development of their code!

Bitcoin

This breakdown on Bitcoin's GitHub page shows that 3 proposed code changes were accepted into the codebase. These updates will be placed in a "staging" branch where it can be tested, quite thoroughly when necessary, to ensure stability and safety. Eventually, they will be moved to the master branch and published in an update.

The latest Bitcoin core release was November 24, 2019. Version 0.19.0.1. 
https://github.com/bitcoin/bitcoin/releases/tag/v0.19.0.1

There was also an issue closed, meaning a bug reported by someone was fixed!

Ethereum

The Solidity repository is the basis of smart contract code deployed on the Ethereum network. It likewise has new pull requests and 4 closed today. It's good to see the opening of new issues, as this means people in the community and developers are actively reporting problems to be fixed.

The latest Solidity release was just 10 days ago, version 0.6.2. 

You can see a lot of updates happening across multiple Ethereum projects here
https://github.com/ethereum/

Ripple

For fun we compare to Ripple on Github, which has a new issue reported and one proposed change today.

Its latest release was 1.4.0 on January 3.
https://github.com/ripple/rippled/releases/tag/1.4.0