Fixed -Wcast-qual warning from GCC

[orbitcowboy]

This fixes following warning from GCC

../hash-library/sha256.cpp: In member function ‘void SHA256::processBlock(const void*)’:
../hash-library/sha256.cpp:110:27: warning: cast from type ‘const void*’ to type ‘uint32_t*’ {aka ‘unsigned int*’} casts away qualifiers [-Wcast-qual]
  110 |   const uint32_t* input = (uint32_t*) data;
      |                           ^~~~~~~~~~~~~~~~