slapos-sr-testing: add slapos.toolbox version

software/slapos-sr-testing/software.cfg

@@ -361,6 +361,9 @@ extra =
 [versions]
 # slapos.core is used from the clone always
 slapos.core =
+# in stack/monitor, slapos.toolbox is equal to nothing in order to use another repository
+# we have to specify the version here otherwise it will fail since eggs are not pinned
+slapos.toolbox = 0.123
 # Various needed versions
 Pillow = 5.3.0
 PyNaCl = 1.3.0