Build GMP and MPFR as well in rtd

Author: oscarbenjamin

.readthedocs.yaml

@@ -10,13 +10,9 @@ build:
   os: ubuntu-24.04
   tools:
     python: "3.12"
-  apt_packages:
-    - libgmp-dev
-    - libmpfr-dev
-    - xz-utils
-    - ninja-build
   commands:
-    - bin/build_dependencies_unix.sh --skip-gmp --skip-mpfr
+    - spin --help
+    - bin/build_dependencies_unix.sh --use-gmp-github-mirror
     - spin build -- --pkg-config-path=.local/lib/pkgconfig -Dadd_flint_rpath=true
     - spin docs
     - mv doc/build/html $READTHEDOCS_OUTPUT/html