Prepare for v1.0.3 (#99)

Below is the draft release notes:

## What's Changed
* Add migration guide doc by @emcfarlane in
#74
* Set --debug when the action is using debug logging by @emcfarlane in
#78
* Set --source-control-url on push so that the push action now works by
default on enterprise GitHub instances by @nicksnyder in
#86

## New Contributors
* @doriable made their first contribution in
#98

**Full Changelog**:
v1.0.2...v1.0.3

Author: emcfarlane

package-lock.json

@@ -1,6 +1,6 @@
 {
   "name": "buf-action",
-  "version": "1.0.2",
+  "version": "1.0.3",
   "description": "GitHub Action for buf",
   "main": "src/main.ts",
   "scripts": {