cargo: bump cc from 1.1.15 to 1.1.23 in /src/exercises/bare-metal/rtc in the patch group (#2391)

Bumps the patch group in /src/exercises/bare-metal/rtc with 1 update:
[cc](https://github.com/rust-lang/cc-rs).

Updates `cc` from 1.1.15 to 1.1.23

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

src/exercises/bare-metal/rtc/Cargo.lock

@@ -15,4 +15,4 @@ smccc = "0.1.1"
 spin = "0.9.8"
 
 [build-dependencies]
-cc = "1.1.15"
+cc = "1.1.23"