Revert "ci: Run sage prover on CI"

This reverts commit d8d54859ed138a8ed9a8486d847155211c9f4a7d.

.cirrus.yml

@@ -371,10 +371,3 @@ task:
     - g++ -Werror include/*.h
     - clang -Werror -x c++-header include/*.h
     - /opt/msvc/bin/x64/cl.exe -c -WX -TP include/*.h
-
-task:
-  name: "sage prover"
-  << : *LINUX_CONTAINER
-  test_script:
-    - cd sage
-    - sage prove_group_implementations.sage

ci/linux-debian.Dockerfile

@@ -21,8 +21,7 @@ RUN apt-get update && apt-get install --no-install-recommends -y \
         gcc-aarch64-linux-gnu libc6-dev-arm64-cross libc6-dbg:arm64 \
         gcc-powerpc64le-linux-gnu libc6-dev-ppc64el-cross libc6-dbg:ppc64el \
         gcc-mingw-w64-x86-64-win32 wine64 wine \
-        gcc-mingw-w64-i686-win32 wine32 \
-        sagemath
+        gcc-mingw-w64-i686-win32 wine32
 
 WORKDIR /root