chore(deps): pin mull to release v0.22.0 (#428)

chore: pin mull to release 0.22.0

Co-authored-by: EkelmansPh <58972933+EkelmansPh@users.noreply.github.com>

Author: rjaegers

.devcontainer/cpp/Dockerfile

@@ -4,7 +4,7 @@ ARG BATS_VERSION=1.10.0
 ARG CCACHE_VERSION=4.9.1
 ARG CLANG_VERSION=17
 ARG DOCKER_VERSION=26.1.1
-ARG MULL_VERSION=main
+ARG MULL_VERSION=0.22.0
 ARG INCLUDE_WHAT_YOU_USE_VERSION=0.21
 ARG XWIN_VERSION=0.5.2