Prepare 9.0.0b4 release

material/base.html

@@ -22,7 +22,7 @@
         <link rel="canonical" href="{{ page.canonical_url }}">
       {% endif %}
       <link rel="icon" href="{{ config.theme.favicon | url }}">
-      <meta name="generator" content="mkdocs-{{ mkdocs_version }}, mkdocs-material-9.0.0b3">
+      <meta name="generator" content="mkdocs-{{ mkdocs_version }}, mkdocs-material-9.0.0b4">
     {% endblock %}
     {% block htmltitle %}
       {% if page.meta and page.meta.title %}

package-lock.json

 {
   "name": "mkdocs-material",
-  "version": "9.0.0b3",
+  "version": "9.0.0b4",
   "lockfileVersion": 2,
   "requires": true,
   "packages": {
     "": {
       "name": "mkdocs-material",
-      "version": "9.0.0b3",
+      "version": "9.0.0b4",
       "license": "MIT",
       "dependencies": {
         "array-flat-polyfill": "^1.0.1",

package.json

 {
   "name": "mkdocs-material",
-  "version": "9.0.0b3",
+  "version": "9.0.0b4",
   "description": "Documentation that simply works",
   "keywords": [
     "mkdocs",