feat: Fix types for Vue 2.7

The Vue 2.7 type for 'Vue' does not seem to fully match the Vue 2.6
'Vue' type. To cope with this, we also accept the new Vue 2.7
 'ComponentPublicInstance' type.

 Because the Vue 2.7 types refer to ES2015 types like 'Set', the
 tsconfig 'lib' needs to be ES2015 as well. This however should not
 change the compatability of the generated code of this library,
 as we only use ES5-style constructs.

index.ts

@@ -1,10 +1,10 @@
-import type Vue from 'vue';
+import type { ComponentPublicInstance } from 'vue';
 
 // make EventCallback<string|number> = (x:string|number) => void instead of = ((x: string) => void) | ((x: number) => void)
 // see https://www.typescriptlang.org/docs/handbook/2/conditional-types.html#distributive-conditional-types
 type EventCallback<T = unknown> = [T] extends [undefined] ? () => void : (x: T) => void;
 
-type GenericSource<T> = ((this: Vue, eventListener: EventCallback<T>) => void) & {
+type GenericSource<T> = ((this: Vue | ComponentPublicInstance, eventListener: EventCallback<T>) => void) & {
 	addListener: (eventListener: EventCallback<T>) => void;
 	removeListener: (eventListener: EventCallback<T>) => void;
 	emit(data: T): void;
@@ -30,7 +30,7 @@ export function newEventSource<T>(): EventSource<T> {
 		}
 	}
 
-	const result = function (this: Vue /*the child Vue instance*/, cb: EventCallback<T>) {
+	const result = function (this: Vue | ComponentPublicInstance /*the child Vue instance*/, cb: EventCallback<T>) {
 		addListener(cb);
 		this.$once('hook:beforeDestroy', () => {
 			removeListener(cb);

package.json

@@ -35,7 +35,7 @@
 	"devDependencies": {
 		"prettier": "2.5.0",
 		"typescript": "^4.5.2",
-		"vue": "^2.6.14"
+		"vue": "^2.7.8"
 	},
 	"files": [
 		"lib/**/*"

tsconfig.json

@@ -7,7 +7,7 @@
 		"allowJs": true,
 		"moduleResolution": "node",
 		"baseUrl": ".",
-		"lib": ["es5", "DOM"], 
+		"lib": ["ES2015", "DOM"], 
 		"esModuleInterop": true,
 		"declaration": true
 	},