Merge pull request #3412 from ProjectMirador/bump-version

Bump version to 3.1

package.json

 {
   "name": "mirador",
-  "version": "3.0.0",
+  "version": "3.1.0",
   "description": "An open-source, web-based 'multi-up' viewer that supports zoom-pan-rotate functionality, ability to display/compare simple images, and images with annotations.",
   "main": "dist/mirador.min.js",
   "module": "dist/es/src/index.js",