debian: Bump so version to link against new libosmovty2

Debian doesn't have reverse dependencies so we need to bump the
SO version to have libosmoabis and libosmotrau link against our
new version.
diff --git a/src/Makefile.am b/src/Makefile.am
index 5135d35..b24f2cf 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -1,7 +1,7 @@
 # This is _NOT_ the library release version, it's an API version.
 # Please read Chapter 6 "Library interface versions" of the libtool documentation before making any modification
-ABIS_LIBVERSION=4:0:0
-TRAU_LIBVERSION=0:0:0
+ABIS_LIBVERSION=5:0:0
+TRAU_LIBVERSION=1:0:0
 
 AM_CPPFLAGS = $(all_includes) -I$(top_srcdir)/include -I$(top_builddir)
 AM_CFLAGS= -Wall $(LIBOSMOCORE_CFLAGS) $(LIBOSMOGSM_CFLAGS) $(LIBOSMOVTY_CFLAGS) $(COVERAGE_CFLAGS)