Add back support for Ember 3.16

As discussed in #33 (comment), this introduces a conditional to support Ember 3.16+ while still using the latest modifier capabilities when possible. `@embroider/macros` was chosen for this instead of the usual `ember-compatibility-helpers`, as that seems to more future-proof solution to me, especially allowing an easier transition to an eventual native "v2" addon.

.github/workflows/ci.yml

@@ -39,7 +39,8 @@ jobs:
       fail-fast: true
       matrix:
         ember-try-scenario:
-          - ember-lts-3.22
+          - ember-lts-3.16
+          - ember-lts-3.20
           - ember-release
           - ember-beta
           - ember-canary

README.md

@@ -23,9 +23,9 @@ Please read the [focus-trap](https://github.com/davidtheclark/focus-trap) docume
 
 ## Compatibility
 
-- Ember.js v3.22 or above
-- Ember CLI v2.13 or above
-- Node.js v10 or above
+* Ember.js v3.16 or above
+* Ember CLI v2.13 or above
+* Node.js v10 or above
 
 ## Installation
 

addon/modifiers/focus-trap.js

@@ -3,7 +3,11 @@ import { createFocusTrap as CreateFocusTrap } from 'focus-trap';
 
 export default setModifierManager(
   () => ({
-    capabilities: capabilities('3.22'),
+    capabilities: capabilities(
+      macroCondition(dependencySatisfies('ember-source', '^3.22.0'))
+        ? '3.22'
+        : '3.13'
+    ),
 
     createModifier() {
       return {

config/ember-try.js

@@ -8,10 +8,18 @@ module.exports = async function () {
     useYarn: true,
     scenarios: [
       {
-        name: 'ember-lts-3.22',
+        name: 'ember-lts-3.16',
         npm: {
           devDependencies: {
-            'ember-source': '~3.22.2',
+            'ember-source': '~3.16.0',
+          },
+        },
+      },
+      {
+        name: 'ember-lts-3.20',
+        npm: {
+          devDependencies: {
+            'ember-source': '~3.20.5',
           },
         },
       },