feat: remove sync hooks support

src/plugins/hooks.js

@@ -137,10 +137,6 @@ async function fireFilterHook(hook, hookList, params) {
 					payload => resolve(payload),
 					err => reject(err)
 				);
-				return;
-			}
-			if (returned) {
-				resolve(returned);
 			}
 		});
 	}

test/plugins.js

@@ -47,7 +47,7 @@ describe('Plugins', () => {
 		});
 	});
 
-	it('should register and fire a filter hook having 3 methods, one returning a promise, one calling the callback and one just returning', async () => {
+	it('should register and fire a filter hook having 2 methods, one returning a promise, one calling the callback', async () => {
 		function method1(data, callback) {
 			data.foo += 1;
 			callback(null, data);
@@ -58,14 +58,9 @@ describe('Plugins', () => {
 				resolve(data);
 			});
 		}
-		function method3(data) {
-			data.foo += 1;
-			return data;
-		}
 
 		plugins.hooks.register('test-plugin', { hook: 'filter:test.hook2', method: method1 });
 		plugins.hooks.register('test-plugin', { hook: 'filter:test.hook2', method: method2 });
-		plugins.hooks.register('test-plugin', { hook: 'filter:test.hook2', method: method3 });
 
 		const data = await plugins.hooks.fire('filter:test.hook2', { foo: 1 });
 		assert.strictEqual(data.foo, 8);