fix: sync cli version for 0.0.43

Author: Sunrisepeak

.agents/docs/2026-06-02-dotted-dependency-selectors.md

@@ -275,6 +275,9 @@ mcpp test
   pass locally.
 - 2026-06-02: Bumped the pending release version to `0.0.43` and added the
   changelog entry for dotted dependency selectors.
+- 2026-06-02: CI exposed that `--version` also uses the hardcoded
+  `MCPP_VERSION` in `src/toolchain/fingerprint.cppm`; synchronized it to
+  `0.0.43`.
 
 Current local checks:
 

src/toolchain/fingerprint.cppm

@@ -18,7 +18,7 @@ import mcpp.toolchain.detect;
 
 export namespace mcpp::toolchain {
 
-inline constexpr std::string_view MCPP_VERSION = "0.0.42";
+inline constexpr std::string_view MCPP_VERSION = "0.0.43";
 
 struct FingerprintInputs {
     Toolchain                       toolchain;