Bump web3 from 1.2.4 to 1.2.6 (#82)

* Bump web3 from 1.2.4 to 1.2.6

Bumps [web3](https://github.com/ethereum/web3.js) from 1.2.4 to 1.2.6.
- [Release notes](https://github.com/ethereum/web3.js/releases)
- [Changelog](https://github.com/ethereum/web3.js/blob/1.x/CHANGELOG.md)
- [Commits](web3/web3.js@v1.2.4...v1.2.6)

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

* Added bignumber.js to dependencies

package.json

@@ -47,7 +47,8 @@
     "web3": "^1.2.4"
   },
   "dependencies": {
-    "@gnosis.pm/dex-contracts": "^0.2.0"
+    "@gnosis.pm/dex-contracts": "^0.2.0",
+    "bignumber.js": "^9.0.0"
   },
   "devDependencies": {
     "@types/bignumber.js": "^5.0.0",