Use GitHub actions for testing Cowboy

Now tested against OTP-24+.
Erlang.mk has been updated as well.

.github/workflows/ci.yaml

@@ -0,0 +1,15 @@
+## Use workflows from ninenines/ci.erlang.mk to test Cowboy.
+
+name: Check Cowboy
+
+on:
+  push:
+  pull_request:
+  schedule:
+      ## Every Monday at 2am.
+      - cron: 0 2 * * 1
+
+jobs:
+  check:
+    name: Cowboy
+    uses: ninenines/ci.erlang.mk/.github/workflows/ci.yaml@master

Makefile

@@ -29,10 +29,10 @@ dep_gun = git https://github.com/ninenines/gun master
 dep_ci.erlang.mk = git https://github.com/ninenines/ci.erlang.mk master
 DEP_EARLY_PLUGINS = ci.erlang.mk
 
-AUTO_CI_OTP ?= OTP-LATEST-22+
+AUTO_CI_OTP ?= OTP-LATEST-24+
 AUTO_CI_HIPE ?= OTP-LATEST
 # AUTO_CI_ERLLVM ?= OTP-LATEST
-AUTO_CI_WINDOWS ?= OTP-LATEST-22+
+AUTO_CI_WINDOWS ?= OTP-LATEST-24+
 
 # Hex configuration.