BIP-0386: Fix uncompressed private key test vector

Base58 in the WIF format is case sensitive. The following Test Vector will result in an error indicating the WIF version is invalid, regardless of the compression state of the public key. ``` 5kyzdueo39z3fprtux2qbbwgnnp5ztd7yyr2sc1j299sbcnwjss ``` The following is probably what was intended: ``` 5KYZdUEo39z3FPrtuX2QbbwGnNP5zTd7yyr2SC1j299sBCnWjss ```

Specification

5kyzdueo39z3fprtux2qbbwgnnp5ztd7yyr2sc1j299sbcnwjss

5KYZdUEo39z3FPrtuX2QbbwGnNP5zTd7yyr2SC1j299sBCnWjss