Fix package.json files field

(cherry picked from commit 735c03fc)

contracts/package.json

@@ -5,8 +5,7 @@
   "files": [
     "**/*.sol",
     "/build/contracts/*.json",
-    "!/mocks",
-    "!/examples"
+    "!/mocks/**/*"
   ],
   "scripts": {
     "prepare": "bash ../scripts/prepare-contracts-package.sh",

package.json

@@ -5,8 +5,7 @@
   "files": [
     "/contracts/**/*.sol",
     "/build/contracts/*.json",
-    "!/contracts/mocks",
-    "/test/behaviors"
+    "!/contracts/mocks/**/*"
   ],
   "bin": {
     "openzeppelin-contracts-migrate-imports": "scripts/migrate-imports.js"