chore: fix release script

Author: imabhichow

.releaserc

@@ -57,7 +57,7 @@
           }],
           ["@semantic-release/git", {
             "assets": ["./CHANGELOG.md", "./pom.xml", "./README.md"],
-            "message": "AWS Encryption SDK ${nextRelease.version} Release -- $(date +'%Y-%m-%d') \n\n${nextRelease.notes}"
+            "message": "AWS Encryption SDK ${nextRelease.version} Release -- ${new Date().toISOString().slice(0, 10)} \n\n${nextRelease.notes}"
           }],
     ],
     "repositoryUrl": "https://github.com/aws/aws-encryption-sdk-java",