Change build tagging from timestamp to git hash

[bs-github]

The build is suffixed with the timestamp in hex format, but the git commit hash may be more helpful.

Using the build timestamp as defining fact to identify a build is probably less desirable than something that can point to the used code.

Solution I'd like

• Using the git commit hash on a clean git tree,
• but using the timestamp on a unclean working tree (and indicating an unclean build in the filename)

Additional context

We have to make sure this does not interfere with the build timestamp that is used in the code to make sure the RTC clock is fine.

[bs-github]

maybe this can help: https://github.com/sblantipodi/platformio_version_increment

[okurz]

Maybe the output of git describe can help which includes the latest git tag plus commit number after that and shortened git hash so that the version is always increasing

[bs-github]

With the hint from @okurz, a bit of playing around led to this:

➜  software git:(logging-improvements) ✗ git status
On branch logging-improvements
Your branch is up to date with 'origin/logging-improvements'.

Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git restore <file>..." to discard changes in working directory)
    modified:   src/modules/ac011k/ac011k.cpp
    modified:   src/modules/ac011k/ac011k.h

➜  software git:(logging-improvements) ✗ git describe --dirty="-$(git branch --show-current)-$(date "+%Y-%m-%d-%H:%M:%S")"
warpAC011K-2.0.8-176-g7d3594a1-logging-improvements-2023-02-03-10:07:15

[bs-github]

Adding the build flags in build.cpp could be another improvement, but has the potential of leaking sensitive information.