Add Github Actions support code

.github/main.workflow

@@ -0,0 +1,27 @@
+workflow "Check Irssi" {
+  on = "push"
+  resolves = [
+    "script",
+    "unit_tests",
+  ]
+}
+
+action "install" {
+  uses = "irssi-import/actions-irssi/check-irssi@master"
+  args = "before_install install"
+}
+
+action "script" {
+  uses = "irssi-import/actions-irssi/check-irssi@master"
+  needs = ["install"]
+  args = "before_script script after_script"
+  env = {
+    TERM = "xterm"
+  }
+}
+
+action "unit_tests" {
+  uses = "irssi-import/actions-irssi/check-irssi@master"
+  needs = ["install"]
+  args = "unit_tests after_unit_tests"
+}