fix: Fix of the transaction saving job to handle transactions that do…

… not contain an amount - MEED-8203 - Meeds-io/MIPs#118  (#85)

This change will fix of the transaction saving job to handle transactions that do not contain an amount.

gamification-evm-services/src/main/java/io/meeds/evm/gamification/entity/EvmTransactionEntity.java

@@ -53,7 +53,7 @@ public class EvmTransactionEntity implements Serializable {
   @Column(name = "TRANSACTION_DATE", nullable = false)
   private Long       transactionDate;
 
-  @Column(name = "AMOUNT", nullable = false)
+  @Column(name = "AMOUNT")
   private BigInteger amount;
 
   @Column(name = "TOKEN_ID")