Remove useless subshell from alma9 docker driver script

Since it runs `exec docker ...` as the last step, putting it inside a
subhsell is not so useful.

contrib/alma9_rpmbuild_docker/run.sh

diff --git a/contrib/alma9_rpmbuild_docker/run.sh b/contrib/alma9_rpmbuild_docker/run.sh
index 2ae255c..ba9e228 100755
--- a/contrib/alma9_rpmbuild_docker/run.sh
+++ b/contrib/alma9_rpmbuild_docker/run.sh
@@ -36,7 +36,6 @@
    -i
    -t
 )
-(
-   set -x
-   exec docker run "${docker_args[@]}" "$tag" "$@"
-)
+
+set -x
+exec docker run "${docker_args[@]}" "$tag" "$@"