set T-Echo Card TCXO voltage to 3.0

as per meshcore-dev#3140 and Xinyuan-LilyGO/T-Echo-Lite#14

Author: oltaco

variants/lilygo_techo_card/variant.h

@@ -107,7 +107,7 @@
 #define  P_LORA_NSS                (11)  // P0.11
 #define  SX126X_RXEN               (33)  // P1.01
 #define  SX126X_TXEN               (27)  // P0.27
-#define  SX126X_DIO3_TCXO_VOLTAGE  (1.8f)
+#define  SX126X_DIO3_TCXO_VOLTAGE  (3.0f)
 
 
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