`nimble search bignum` already points to another fork, so the nimble pkg name should be changed

/cc @kaushalmodi to avoid confusion with the fork https://github.com/kaushalmodi/bignum that's already published on nimble, either this package or https://github.com/kaushalmodi/bignum should rename their nimble file; but since nimble bignum already points to https://github.com/kaushalmodi/bignum, IMO the sane option is to rename this nimble to bignum0

nimble search bignum
gmp:
  url:         https://github.com/subsetpark/nim-gmp (git)
  tags:        library, bignum, numbers, math
  description: wrapper for the GNU multiple precision arithmetic library (GMP)
  license:     LGPLv3 or GPLv2
  website:     https://github.com/subsetpark/nim-gmp

bignum:
  url:         https://github.com/kaushalmodi/bignum (git)
  tags:        bignum, gmp, wrapper
  description: Wrapper around the GMP bindings for the Nim language.
  license:     MIT
  website:     https://github.com/kaushalmodi/bignum

BN:
  url:         https://github.com/MerosCrypto/BN (git)
  tags:        bignumber, multiprecision, imath
  description: A Nim Wrapper of the imath BigNumber library.
  license:     MIT

also @kaushalmodi could you please enable issues for your fork https://github.com/kaushalmodi/bignum, especially since it's the "official" backing of nimble install bignum ?

FedeOmoto / bignum

`nimble search bignum` already points to another fork, so the nimble pkg name should be changed #3