.builds: fix apple builder

The python package is gone, we may not need it and/or Debian installs
python3 by default.

curl is needed for automatically applying patches from the mailing list.

Signed-off-by: Elias Naur <mail@eliasnaur.com>

.builds/apple.yml

@@ -2,7 +2,7 @@ image: debian/testing
 packages:
  - clang
  - cmake
- - python
+ - curl
  - autoconf
  - libxml2-dev
  - libssl-dev