function tapBranchHash(a, b) {
  return bcrypto.taggedHash('TapBranch', tools.concat([a, b]));
}
Computes the TapBranch hash by concatenating two buffers and applying the 'TapBranch' tagged hash algorithm.

@param a - The first buffer.
@param b - The second buffer.
@returns The TapBranch hash of the concatenated buffers.