test(snabbkaffe): Update to latest snabbkaffe

In particular, this should remove the flaky snabbkaffe failures in
persistent session SUITE where the snabbkaffe_nemesis is trying to
make an ets:lookup in a table that no longer exists.

apps/emqx/rebar.config

@@ -20,7 +20,7 @@
     , {hocon, {git, "https://github.com/emqx/hocon.git", {tag, "0.22.0"}}}
     , {pbkdf2, {git, "https://github.com/emqx/erlang-pbkdf2.git", {tag, "2.0.4"}}}
     , {recon, {git, "https://github.com/ferd/recon", {tag, "2.5.1"}}}
-    , {snabbkaffe, {git, "https://github.com/kafka4beam/snabbkaffe.git", {tag, "0.15.0"}}}
+    , {snabbkaffe, {git, "https://github.com/kafka4beam/snabbkaffe.git", {tag, "0.16.0"}}}
     ]}.
 
 {plugins, [{rebar3_proper, "0.12.1"}]}.

rebar.config

@@ -63,7 +63,7 @@
     , {rulesql, {git, "https://github.com/emqx/rulesql", {tag, "0.1.4"}}}
     , {observer_cli, "1.7.1"} % NOTE: depends on recon 2.5.x
     , {getopt, "1.0.2"}
-    , {snabbkaffe, {git, "https://github.com/kafka4beam/snabbkaffe.git", {tag, "0.15.0"}}}
+    , {snabbkaffe, {git, "https://github.com/kafka4beam/snabbkaffe.git", {tag, "0.16.0"}}}
     , {hocon, {git, "https://github.com/emqx/hocon.git", {tag, "0.22.0"}}}
     , {emqx_http_lib, {git, "https://github.com/emqx/emqx_http_lib.git", {tag, "0.4.1"}}}
     , {esasl, {git, "https://github.com/emqx/esasl", {tag, "0.2.0"}}}