macOS builds in Github don't utilise ccache

[vadi2]

Brief summary of issue / Description of requested feature:

macOS builds in Github aren't making use of ccache, which makes them really slow. Stats for a typical build where you can see 75%+ calls missing it:

Cacheable calls:    459 / 543 (84.53%)
  Hits:             108 / 459 (23.53%)
    Direct:          40 / 108 (37.04%)
    Preprocessed:    68 / 108 (62.96%)
  Misses:           351 / 459 (76.47%)
Uncacheable calls:   84 / 543 (15.47%)
Local storage:
  Cache size (GiB): 0.3 / 5.0 ( 5.58%)
  Hits:             108 / 459 (23.53%)
  Misses:           351 / 459 (76.47%)

https://github.com/Mudlet/Mudlet/actions/runs/7940398224/job/21681627145?pr=7078#step:23:1

Steps to reproduce the issue / Reasons for adding feature:

Quicker builds for macOS

Error output / Expected result of feature

Stats are as high as Linux:

 Summary:
  Hits:             306 /  412 (74.27 %)
    Direct:         302 /  412 (73.30 %)
    Preprocessed:     4 /  110 (3.64 %)
  Misses:           106
    Direct:         110
    Preprocessed:   106
  Uncacheable:       19
Primary storage:
  Hits:             711 /  824 (86.29 %)
  Misses:           113
  Cache size (GB): 0.13 / 5.00 (2.58 %)

Extra information, such as the Mudlet version, operating system and ideas for how to solve / implement: