deps/BSSGP: Use specific commit hash

Using "master" doesn't really work as the local master branch already
exists even if we change the 'remote' to a different URL, see
https://gerrit.osmocom.org/c/osmo-ttcn3-hacks/+/21587

Change-Id: Id5f5ba52dbc9cd51dda2e91391c901b56756e2db
diff --git a/deps/Makefile b/deps/Makefile
index 73b3283..1f2560b 100644
--- a/deps/Makefile
+++ b/deps/Makefile
@@ -82,7 +82,7 @@
 titan.ProtocolEmulations.M3UA_commit=		f086e78d74defa044d864f17adaad9433fedc961
 titan.ProtocolEmulations.SCCP_commit=	 	R.7.A-9-g9e70fba
 titan.ProtocolModules.BSSAPP_v7.3.0_commit=	R.2.A-4-g20cfaf8
-titan.ProtocolModules.BSSGP_v13.0.0_commit=	master
+titan.ProtocolModules.BSSGP_v13.0.0_commit=	e97d92a8b66bec399babea52f593771b76cb175a
 titan.ProtocolModules.BSSMAP_commit=		master
 titan.ProtocolModules.DNS_commit=		R.7.B
 titan.ProtocolModules.GRE_commit=		R.2.A-5-g654c446