Release 0.0.8

• #18 Use fastcall protocol to accelerate argument parsing. Small JSON will parse faster than before.
• #19 Support writing and reading UTF-8 cache. Largely improve performance. Add is_write_cache argument to dumps_to_bytes, and ssrjson.write_utf8_cache function. They are used for controlling the cache writing behavior. More details can be found in README.
• Internal refactors and fixes:
  • Use an accurate way to calculate the actual buffer size to reserve.
  • Statically assert 64-bits platform and having IEEE754 double.
  • Other small changes