Fix error which crept in due to daylight savings and me being dumb

(clever).

src/main.zig

@@ -284,7 +284,7 @@ pub const DateTime = struct {
         // days plus some remainder. So we take self.days - 1 for our calculation
         seconds += @as(i64, self.day - 1) * SECONDS_PER_DAY;
         if (self.hour) |h| {
-            seconds += @as(i64, h - 1) * 3600;
+            seconds += @as(i64, h) * 3600;
         }
         if (self.minute) |m| {
             seconds += @as(i64, m) * 60;
@@ -334,7 +334,7 @@ test "to timestamp utc" {
         .year = Year.new(2023),
         .month = .june,
         .day = 13,
-        .hour = 6,
+        .hour = 5,
         .minute = 21,
         .second = 22,
         .tz = .utc,
@@ -347,7 +347,7 @@ test "to timestamp negative offset" {
         .year = Year.new(2023),
         .month = .june,
         .day = 13,
-        .hour = 1,
+        .hour = 0,
         .minute = 21,
         .second = 22,
         .tz = TimeZone.new(-5, null).?,