Add more variation to free-space transaction size testing and update version

Author: kriszyp

package.json

@@ -1,7 +1,7 @@
 {
   "name": "lmdb",
   "author": "Kris Zyp",
-  "version": "3.1.5",
+  "version": "3.1.6",
   "description": "Simple, efficient, scalable, high-performance LMDB interface",
   "license": "MIT",
   "repository": {

test/index.test.js

@@ -428,8 +428,7 @@ describe('lmdb-js', function () {
 					while (random() < 0.95) text += additive;
 					if (random() < 0.4) promise = db.remove(i % 40);
 					else promise = db.put(i % 40, text);
-
-					if (i % 2 == 0) {
+					if (random() < 0.05) {
 						await promise;
 					}
 				}