fix: wrong date comparisons

Author: Pedro González Marcos

src/main/java/io/github/pgmarc/space/contracts/BillingPeriod.java

@@ -2,6 +2,8 @@
 
 import java.time.Duration;
 import java.time.LocalDateTime;
+import java.time.ZoneId;
+import java.time.ZoneOffset;
 import java.time.ZonedDateTime;
 import java.util.Objects;
 import java.util.Optional;
@@ -31,7 +33,7 @@ Duration getDuration() {
     }
 
     boolean isExpired(LocalDateTime dateTime) {
-        return endDate.isAfter(startDate);
+        return endDate.isAfter(ZonedDateTime.of(dateTime, ZoneId.of("UTC")));
     }
 
     boolean isAutoRenewable() {