Bump @openzeppelin/contracts from 3.4.2 to 4.7.3

Bumps [@openzeppelin/contracts](https://github.com/OpenZeppelin/openzeppelin-contracts) from 3.4.2 to 4.7.3.
- [Release notes](https://github.com/OpenZeppelin/openzeppelin-contracts/releases)
- [Changelog](https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/CHANGELOG.md)
- [Commits](OpenZeppelin/openzeppelin-contracts@v3.4.2...v4.7.3)

---
updated-dependencies:
- dependency-name: "@openzeppelin/contracts"
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

package.json

@@ -84,7 +84,7 @@
     "@chainlink/contracts": "^0.1.6",
     "@nomiclabs/hardhat-ethers": "^2.0.2",
     "@nomiclabs/hardhat-waffle": "^2.0.1",
-    "@openzeppelin/contracts": "^3.4.0",
+    "@openzeppelin/contracts": "^4.7.3",
     "eslint-plugin-no-only-tests": "^2.6.0",
     "ethereum-mars": "^0.1.7",
     "ethers": "5.0.18",

packages/contracts-por/package.json

@@ -21,7 +21,7 @@
   },
   "dependencies": {
     "ethereum-mars": "0.2.5",
-    "@openzeppelin/contracts": "3.4.2",
+    "@openzeppelin/contracts": "4.7.3",
     "@chainlink/contracts": "0.1.6"
   },
   "devDependencies": {

yarn.lock

@@ -1762,10 +1762,10 @@
     "@types/sinon-chai" "^3.2.3"
     "@types/web3" "1.0.19"
 
-"@openzeppelin/contracts@3.4.2", "@openzeppelin/contracts@^3.4.0":
-  version "3.4.2"
-  resolved "https://registry.yarnpkg.com/@openzeppelin/contracts/-/contracts-3.4.2.tgz#d81f786fda2871d1eb8a8c5a73e455753ba53527"
-  integrity sha512-z0zMCjyhhp4y7XKAcDAi3Vgms4T2PstwBdahiO0+9NaGICQKjynK3wduSRplTgk4LXmoO1yfDGO5RbjKYxtuxA==
+"@openzeppelin/contracts@4.7.3", "@openzeppelin/contracts@^4.7.3":
+  version "4.7.3"
+  resolved "https://registry.yarnpkg.com/@openzeppelin/contracts/-/contracts-4.7.3.tgz#939534757a81f8d69cc854c7692805684ff3111e"
+  integrity sha512-dGRS0agJzu8ybo44pCIf3xBaPQN/65AIXNgK8+4gzKd5kbvlqyxryUYVLJv7fK98Seyd2hDZzVEHSWAh0Bt1Yw==
 
 "@resolver-engine/core@^0.3.3":
   version "0.3.3"