Fix ethers.js version override (the package is just called 'ethers')

package.json

@@ -47,6 +47,6 @@
     },
     "resolutions": {
         "ethereumjs-tx": "0xProject/ethereumjs-tx#fake-tx-include-signature-by-default",
-        "ethers.js": "0xproject/ethers.js#eip-838-reasons"
+        "ethers": "0xproject/ethers.js#eip-838-reasons"
     }
 }

yarn.lock

@@ -4190,7 +4190,7 @@ ethereumjs-wallet@~0.6.0:
     utf8 "^2.1.1"
     uuid "^2.0.1"
 
-ethers.js@0xproject/ethers.js#eip-838-reasons:
+ethers@0xproject/ethers.js#eip-838-reasons, ethers@^3.0.15:
   version "3.0.18"
   resolved "https://codeload.github.com/0xproject/ethers.js/tar.gz/3cc32db979b308b636cddb812b6418f8256865ff"
   dependencies:
@@ -4205,21 +4205,6 @@ ethers.js@0xproject/ethers.js#eip-838-reasons:
     uuid "2.0.1"
     xmlhttprequest "1.8.0"
 
-ethers@^3.0.15:
-  version "3.0.15"
-  resolved "https://registry.yarnpkg.com/ethers/-/ethers-3.0.15.tgz#7cdea4e23025681f69f575bf481b227315e0e7ab"
-  dependencies:
-    aes-js "3.0.0"
-    bn.js "^4.4.0"
-    elliptic "6.3.3"
-    hash.js "^1.0.0"
-    inherits "2.0.1"
-    js-sha3 "0.5.7"
-    scrypt-js "2.0.3"
-    setimmediate "1.0.4"
-    uuid "2.0.1"
-    xmlhttprequest "1.8.0"
-
 ethjs-abi@0.1.8:
   version "0.1.8"
   resolved "https://registry.yarnpkg.com/ethjs-abi/-/ethjs-abi-0.1.8.tgz#cd288583ed628cdfadaf8adefa3ba1dbcbca6c18"