hopefully the license now has a valid spdx name

packagist.org failed to crawl the repo reporting...
```
Reading composer.json of darksparrow/deegraph-php (master)
Importing branch master (dev-master)
Skipped branch master, Invalid package information:
License "Mozilla Public License Version 2.0" is not a valid SPDX license identifier, see https://spdx.org/licenses/ if you use an open license.
If the software is closed-source, you may use "proprietary" as license.
```

composer.json

@@ -2,7 +2,7 @@
     "name": "darksparrow/deegraph-php",
     "description": "Deegraph Interactions Wrapper",
     "type": "library",
-    "license": "Mozilla Public License Version 2.0",
+    "license": "Mozilla Public License 2.0",
     "authors": [
         {
             "name": "Cerys Lewis",