Enable FreeBSD testing

Also use the new ghcup for bootstrapping GHC in install_deps.

.gitlab/before_script/freebsd/install_deps.sh

@@ -0,0 +1,23 @@
+#!/bin/sh
+
+set -eux
+
+# pkg install --force --yes --no-repo-update curl gcc gmp gmake ncurses perl5 libffi libiconv
+
+. "$( cd "$(dirname "$0")" ; pwd -P )/../../ghcup_env"
+
+curl -sSfL https://downloads.haskell.org/~ghcup/x86_64-portbld-freebsd-ghcup > ./ghcup-bin
+chmod +x ghcup-bin
+
+mkdir -p "${GHCUP_INSTALL_BASE_PREFIX}"/.ghcup/bin
+# ./ghcup-bin install ${GHC_VERSION}
+# ./ghcup-bin install-cabal ${CABAL_VERSION}
+# ./ghcup-bin set ${GHC_VERSION}
+
+# install cabal-3.2.0.0
+curl -sSfL -o freebsd.tar.xz 'https://hasufell.de/f/48aa72dcfaff4c3ea452/?dl=1'
+tar xf freebsd.tar.xz
+cp cabal "${GHCUP_INSTALL_BASE_PREFIX}/.ghcup/bin/cabal"
+chmod +x "${GHCUP_INSTALL_BASE_PREFIX}/.ghcup/bin/cabal"
+
+exit 0