Update to go version 20

[Noofbiz]

Update the tests to use go20.x

• Updated a test to pass. It was failing due to a floating-point rounding difference, so I adjusted the test to not be on an edge so rounding wouldn't affect it.
• Updated the go version in GitHub actions to 20
• Removed the go11 variables as they are unnecessary with the latest go versions
• Removed the go get call for coverage because it is now included in the regular go tool