Enable colour diagnostics in CI

At least for CMake.

.github/workflows/create-release-artifacts.yml

@@ -4,6 +4,10 @@ on:
     tags:
       - v[0-9]*
 
+env:
+  CLICOLOR_FORCE: 1 # Tells CMake to have colored output.
+  CMAKE_COLOR_DIAGNOSTICS: ON # Tells CMake-generated build systems to have colored output.
+
 jobs:
   windows:
     runs-on: windows-2022

.github/workflows/testing.yml

@@ -3,6 +3,10 @@ on:
   - push
   - pull_request
 
+env:
+  CLICOLOR_FORCE: 1 # Tells CMake to have colored output.
+  CMAKE_COLOR_DIAGNOSTICS: ON # Tells CMake-generated build systems to have colored output.
+
 jobs:
   unix:
     strategy:
@@ -359,6 +363,7 @@ jobs:
       - name: Build & test using CMake on FreeBSD
         uses: vmactions/freebsd-vm@v1
         with:
+          envs: CLICOLOR_FORCE CMAKE_COLOR_DIAGNOSTICS
           release: "14.3"
           usesh: true
           prepare: |