update built-in solc 0.8.15

Author: tintinweb

package-lock.json

@@ -30,7 +30,7 @@
     "minimist": "^1.2.5",
     "readline-sync": "^1.4.10",
     "request": "^2.88.2",
-    "solc": "^0.8.13",
+    "solc": "^0.8.15",
     "sync-request": "^6.1.0",
     "vorpal": "^1.12.0",
     "web3": "^1.5.2"