Obtain git hash from git_version crate

[Urhengulas]

Use the git_version crate for obtaining the git hash, instead of the custom build-script we used so far. Similar to knurling-rs/probe-run#221

[Urhengulas]

@japaric We discussed the possibility to completely get rid of build.rs with this change. But since we still want to alter the linker-script and insert the version, this isn't really possible is it?

[japaric]

@Urhengulas correct, we need the build script to put the defmt.x linker script in the project's target directory otherwise the linker won't find it. So we want to keep this line even if we don't modify defmt.x in the build script.

defmt/build.rs

Line 38 in fde2aab

fs::write(out.join("defmt.x"), linker_script)?;

[Urhengulas]

@Urhengulas correct, we need the build script to put the defmt.x linker script in the project's target directory otherwise the linker won't find it. So we want to keep this line even if we don't modify defmt.x in the build script.

defmt/build.rs

Line 38 in fde2aab

fs::write(out.join("defmt.x"), linker_script)?;

But we want to modify it, don't we? To insert the version into it?

[japaric]

But we want to modify it, don't we? To insert the version into it?

yes, we want to continue doing that. (the last line of my last comment was referring to an hypothetical scenario)