Set version number to 2.1.20

This prevents merge conflicts

node_modules/.package-lock.json

@@ -1,6 +1,6 @@
 {
   "name": "codeql",
-  "version": "1.1.19",
+  "version": "2.1.20",
   "lockfileVersion": 2,
   "requires": true,
   "packages": {

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "codeql",
-  "version": "1.1.19",
+  "version": "2.1.20",
   "lockfileVersion": 2,
   "requires": true,
   "packages": {
     "": {
       "name": "codeql",
-      "version": "1.1.19",
+      "version": "2.1.20",
       "license": "MIT",
       "dependencies": {
         "@actions/artifact": "^1.0.0",

package.json

@@ -1,6 +1,6 @@
 {
   "name": "codeql",
-  "version": "1.1.19",
+  "version": "2.1.20",
   "private": true,
   "description": "CodeQL action",
   "scripts": {