Update master version number. (#9880)

Author: karthiknadig

package-lock.json

@@ -2,7 +2,7 @@
     "name": "python",
     "displayName": "Python",
     "description": "Linting, Debugging (multi-threaded, remote), Intellisense, Jupyter Notebooks, code formatting, refactoring, unit tests, snippets, and more.",
-    "version": "2020.2.0-rc",
+    "version": "2020.3.0-dev",
     "languageServerVersion": "0.5.30",
     "publisher": "ms-python",
     "author": {