message: Add static cast to avoid implicit double promotion.
  Add static cast from float to double in flexbuffers.h to avoid implicit double promotion error. This error is surfacing during the tensorflow lite for microcontrollers build since we enabled -Werror and -Wdouble-promotion.
diff: @@ -1417,7 +1417,10 @@ class Builder FLATBUFFERS_FINAL_CLASS {
  Value(uint64_t u, Type t, BitWidth bw)
  : u_(u), type_(t), min_bit_width_(bw) {}
  - Value(float f) : f_(f), type_(FBT_FLOAT), min_bit_width_(BIT_WIDTH_32) {}
  + Value(float f)
  + : f_(static_cast<double>(f)),
  + type_(FBT_FLOAT),
  + min_bit_width_(BIT_WIDTH_32) {}
  Value(double f) : f_(f), type_(FBT_FLOAT), min_bit_width_(WidthF(f)) {}
  uint8_t StoredPackedType(BitWidth parent_bit_width_ = BIT_WIDTH_8) const {
  