Fix make install copying the wrong binaries

While testing
https://gitlab.com/gitlab-org/build/CNG/-/merge_requests/1062, we
found `make install` was not copying the right binaries, such as
`gitlab-shell-authorized-keys-check`.

This might have originally been written with a single binary in mind
(https://gitlab.com/gitlab-org/gitlab-shell/-/issues/207).

Changelog: fixed

Makefile

@@ -66,7 +66,6 @@ install: compile
 	mkdir -p $(DESTDIR)$(PREFIX)/bin/
 	install -m755 bin/check $(DESTDIR)$(PREFIX)/bin/check
 	install -m755 bin/gitlab-shell $(DESTDIR)$(PREFIX)/bin/gitlab-shell
-	install -m755 bin/gitlab-shell $(DESTDIR)$(PREFIX)/bin/gitlab-shell-authorized-keys-check
-	install -m755 bin/gitlab-shell $(DESTDIR)$(PREFIX)/bin/gitlab-shell-authorized-principals-check
-	install -m755 bin/gitlab-shell $(DESTDIR)$(PREFIX)/bin/gitlab-sshd
-
+	install -m755 bin/gitlab-shell-authorized-keys-check $(DESTDIR)$(PREFIX)/bin/gitlab-shell-authorized-keys-check
+	install -m755 bin/gitlab-shell-authorized-principals-check $(DESTDIR)$(PREFIX)/bin/gitlab-shell-authorized-principals-check
+	install -m755 bin/gitlab-sshd $(DESTDIR)$(PREFIX)/bin/gitlab-sshd