remove testing

esphome/components/sha256/sha256.cpp

@@ -78,12 +78,6 @@ void SHA256::calculate() {
 #error "SHA256 not supported on this platform"
 #endif
 
-std::string SHA256::get_hex_string() {
-  char buf[65];
-  this->get_hex(buf);
-  return std::string(buf);
-}
-
 }  // namespace esphome::sha256
 
 #endif  // Platform check

esphome/components/sha256/sha256.h

@@ -33,8 +33,6 @@ class SHA256 : public esphome::HashBase {
 
   void calculate() override;
 
-  std::string get_hex_string();
-
   /// Get the size of the hex output (64 for SHA256)
   size_t get_hex_size() const override { return 64; }