refactor: remove CORS proxy from env

Author: greenlucid

.env.example

@@ -23,13 +23,6 @@ REACT_APP_TX_BATCHER_ADDRESSES={"5":"0x394E870A068E9C623aC6Bc51d53cc4a040420e8e"
 REACT_APP_SUBGRAPH_URL={"1":"https://api.thegraph.com/subgraphs/name/kleros/curate","5":"https://api.thegraph.com/subgraphs/name/greenlucid/curate-goerli","42":"https://api.thegraph.com/subgraphs/name/eccentricexit/light-curate-kovan-ii","100":"https://api.thegraph.com/subgraphs/name/eccentricexit/curate-xdai-ii","421611":"https://api.thegraph.com/subgraphs/name/greenlucid/curate-arbitrum-rinkeby"}
 REACT_APP_REJECT_ALL_POLICY_URI="/ipfs/QmZ7RVU7re1g8nXDbAFMHV99pyie3dn4cY7Ga2X4h8mDpV/reject-all-policy.pdf"
 
-# Twitter client
-REACT_APP_BEARER_TOKEN=
-
-# CORS Proxy
-# Do not include / at the end.
-REACT_APP_CORS_PROXY_URL=https://curate-cors.herokuapp.com
-
 # All fields below this line are optional -------------
 
 REACT_APP_WALLETCONNECT_BRIDGE_URL=https://bridge.walletconnect.org