ci: add gmake to FreeBSD CI dependencies

Install GNU make (gmake) in the FreeBSD workflow prepare step to support building and testing, as the process requires GNU make utilities alongside existing tools like jq and GNU coreutils.

Author: mattsu2020

.github/workflows/freebsd.yml

@@ -49,7 +49,7 @@ jobs:
         sync: rsync
         copyback: false
         # We need jq and GNU coreutils to run show-utils.sh and bash to use inline shell string replacement
-        prepare: pkg install -y curl sudo jq coreutils bash
+        prepare: pkg install -y curl gmake sudo jq coreutils bash
         run: |
           ## Prepare, build, and test
           # implementation modelled after ref: <https://github.com/rust-lang/rustup/pull/2783>