- Download ca-bundle.crt from https://github.com/bagder/ca-bundle/blob/e9175fec5d0c4d42de24ed6d84a06d504d5e5a09/ca-bundle.crt
- Put the file in c:\wamp64\
Change php.ini to the following
curl.cainfo="C:/wamp64/ca-bundle.crt"
openssl.cafile="C:/wamp64/ca-bundle.crt"
This worked for me.
Note : You have to restart server after doing above process.