chore: GitHub action workflows use node version from .nvmrc

[kunalnagar]

• Instead of updating node versions across multiple files, you only need to update the .nvmrc and the same version will be picked up by GitHub actions.
• Matrix strategy testing was only using one version of node. Instead, updated it to pick up the version from the .nvmrc. In the future, if Tuta needs to be matrix tested, multiple node versions can be used.