Fix Makefile errors that prevent builds on macOS (#409)

CHANGELOG.md

@@ -4,6 +4,8 @@ Here's all notable changes and commits to both the configuration repo and the ba
 Many thanks to all those who have submitted issues and pull requests to make this firmware better!
 ## Config repo
 
+14/3/2024 - Fix Makefile errors that prevent builds on macOS [#409](https://github.com/KinesisCorporation/Adv360-Pro-ZMK/pull/409)
+
 18/2/2024 - Fix version.dtsi reset after build when running local builds [#385](https://github.com/KinesisCorporation/Adv360-Pro-ZMK/pull/385)
 
 12/2/2024 - Update GitHub build workflow to use the latest actions [#376](https://github.com/KinesisCorporation/Adv360-Pro-ZMK/pull/376)

Makefile

@@ -1,8 +1,7 @@
-DOCKER := "$(shell { command -v podman || command -v docker; })"
-TIMESTAMP := "$(shell date -u +"%Y%m%d%H%M")"
-COMMIT := "$(shell git rev-parse --short HEAD 2>/dev/null)"
-detected_OS := "$(shell uname)"  # Classify UNIX OS
-ifeq ($(strip $(detected_OS)),Darwin) #We only care if it's OS X
+DOCKER := $(shell { command -v podman || command -v docker; })
+TIMESTAMP := $(shell date -u +"%Y%m%d%H%M")
+COMMIT := $(shell git rev-parse --short HEAD 2>/dev/null)
+ifeq ($(shell uname),Darwin)
 SELINUX1 :=
 SELINUX2 :=
 else