Add changelog

Author: alextwoods

.changes/next-release/bugfix-IAMPolicyBuilder-60dd1f5.json

@@ -0,0 +1,6 @@
+{
+    "type": "bugfix",
+    "category": "IAM Policy Builder",
+    "contributor": "",
+    "description": "Allow integer AWS account IDs and boolean values when reading IAM policies from JSON with `IamPolicyReader`."
+}