Add a fallback option to output the latest tag

[dhwthompson]

This is available either by running tag-release current or just tag-release with no arguments. I realized I wanted some way to ask "hey, where are we at right now?", and figured that this was a reasonable way to do it. It also seems more approachable than spitting out an error when no arguments are provided, which feels like a useful property to have in a potentially dangerous script.

[dhwthompson]

Documentation for the cryptically-named nargs argument.

[dhwthompson]

Example output:

$ ./tools/tag-release
Most recent tag: v0.7.0-rc5
Run with the `--help` flag for a list of available commands.

[SamLR]

Looks reasonable.

I did spot, though, that this requires python3.8 (for the walrus operator :=) while the default python version on mac is 3.7 I'm not sure if this needs to downgrade? Apaprently the version of python3 that ubuntu ships seems to be 3.8.1

[dhwthompson]

I did spot, though, that this requires python3.8 (for the walrus operator :=) while the default python version on mac is 3.7

That’s a good thought, although I don’t seem to be seeing quite the same picture of macOS Python versioning as you. I couldn’t find any official documentation, but from a bit of Stack Overflow spelunking and checking on my own machine, it looks like the last few versions have been:

OS version	Name	Python version
10.15	Catalina	3.7.3
11	Big Sur	3.8.2
12	Monterey	3.8.9

I don’t know what distribution of macOS versions our Mac-based developers have, but it seems worth the small amount of effort it would take to de-walrus-ify the code, just in case. I’ll make a follow-up PR.