Use Gun 1.2.0 for tests to avoid OTP-19 issues

And temporarily depend on Cowlib master to confirm everything
works as intended.

Makefile

@@ -15,14 +15,14 @@ CT_OPTS += -ct_hooks cowboy_ct_hook [] # -boot start_sasl
 LOCAL_DEPS = crypto
 
 DEPS = cowlib ranch
-dep_cowlib = git https://github.com/ninenines/cowlib 2.7.1
+dep_cowlib = git https://github.com/ninenines/cowlib master
 dep_ranch = git https://github.com/ninenines/ranch 1.7.1
 
 DOC_DEPS = asciideck
 
 TEST_DEPS = $(if $(CI_ERLANG_MK),ci.erlang.mk) ct_helper gun proper
 dep_ct_helper = git https://github.com/extend/ct_helper master
-dep_gun = git https://github.com/ninenines/gun 1.3.0
+dep_gun = git https://github.com/ninenines/gun 1.2.0
 
 # CI configuration.