Add a changelog

Adds an empty changelog file and a reminder to update it when opening
pull requests.

Also, adds a 1.0.0 version number in the package.json, which is what
we _could_ use for version numbering.

Author: aeisenberg

.github/pull_request_template.md

@@ -1,4 +1,5 @@
 ### Merge / deployment checklist
 
 - [ ] Confirm this change is backwards compatible with existing workflows.
-- [ ] Confirm the [readme](https://github.com/github/codeql-action/blob/master/README.md) has been updated if necessary.
+- [ ] Confirm the [readme](https://github.com/github/codeql-action/blob/main/README.md) has been updated if necessary.
+- [ ] Confirm the [changelog](https://github.com/github/codeql-action/blob/main/CHANGELOG.md) has been updated if necessary.

CHANGELOG.md

@@ -0,0 +1,3 @@
+# CodeQL Action and CodQL Runner Changelog
+
+## [UNRELEASED]

node_modules/.package-lock.json

@@ -1,6 +1,6 @@
 {
   "name": "codeql",
-  "version": "0.0.0",
+  "version": "1.0.0",
   "private": true,
   "description": "CodeQL action",
   "scripts": {