Bump solc from 0.7.0 to 0.8.0

Bumps [solc](https://github.com/ethereum/solc-js) from 0.7.0 to 0.8.0.
- [Release notes](https://github.com/ethereum/solc-js/releases)
- [Commits](ethereum/solc-js@v0.7.0...v0.8.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

package.json

@@ -36,7 +36,7 @@
     "@kleros/erc-792": "^7.0.0",
     "@openzeppelin/test-helpers": "^0.5.7",
     "ganache-cli": "^6.12.0",
-    "solc": "0.7.0",
+    "solc": "0.8.0",
     "solhint": "^3.2.1",
     "solidity-docgen": "^0.5.7",
     "truffle": "^5.1.48",