I use bump2version and I’d like to use variables in my commit message

my .bumpconfiguration.cfg

[bumpversion]
current_version = 13.3.0
commit = True
message = $(git symbolic-ref --short HEAD): bump commit from {current_version} to {new_version}


[bumpversion:file:VERSION]
search = {current_version}
replace = {new_version}

i’d like to use the branch name, but it is not working.

i tried also to set a variable branchName=$(git symbolic-ref –short HEAD) and then set

message = %branchName: bump

but it doesn’t work