v6.0.0: bump version and update changelog

Author: rvagg

CHANGELOG.md

@@ -1,3 +1,12 @@
+v6.0.0 2019-??-??
+=================
+
+* [[`a84b885756`](https://github.com/nodejs/node-gyp/commit/a84b885756)] - **gyp**: fix undefined name: cflags --\> ldflags (Christian Clauss) [#1901](https://github.com/nodejs/node-gyp/pull/1901)
+* [[`2441932dc4`](https://github.com/nodejs/node-gyp/commit/2441932dc4)] - **src,win**: add support for fetching arm64 node.lib (Richard Townsend) [#1875](https://github.com/nodejs/node-gyp/pull/1875)
+* [[`c763ca1838`](https://github.com/nodejs/node-gyp/commit/c763ca1838)] - **(SEMVER-MAJOR)** **doc**: Declare that node-gyp is Python 3 compatible (cclauss) [#1811](https://github.com/nodejs/node-gyp/pull/1811)
+* [[`3d1c60ab81`](https://github.com/nodejs/node-gyp/commit/3d1c60ab81)] - **(SEMVER-MAJOR)** **lib**: accept Python 3 by default (João Reis) [#1844](https://github.com/nodejs/node-gyp/pull/1844)
+* [[`c6e3b65a23`](https://github.com/nodejs/node-gyp/commit/c6e3b65a23)] - **(SEMVER-MAJOR)** **lib**: raise the minimum Python version from 2.6 to 2.7 (cclauss) [#1818](https://github.com/nodejs/node-gyp/pull/1818)
+
 v5.0.4 2019-09-27
 =================
 

package.json

@@ -11,7 +11,7 @@
     "bindings",
     "gyp"
   ],
-  "version": "5.0.4",
+  "version": "6.0.0",
   "installVersion": 9,
   "author": "Nathan Rajlich <[email protected]> (http://tootallnate.net)",
   "repository": {