fix(sqlx-core): allow time::OffsetDateTime to be built from sqlite's CURRENT_TIMESTAMP (#2285)

SQLite's CURRENT_TIMESTAMP keyword fills a DATETIME column as a UTC expressed
string in the following format: "YYYY-MM-DD HH:MM:SS".

Unfortunately, this format lacks the timezone information to safely build
a time::OffsetDateTime.

If all else fails, this patch will try to build it by assuming the missing
timezine is UTC.

sqlx-sqlite/src/types/time.rs

@@ -145,6 +145,10 @@ fn decode_offset_datetime_from_text(value: &str) -> Option<OffsetDateTime> {
         return Some(dt);
     }
 
+    if let Some(dt) = decode_datetime_from_text(value) {
+        return Some(dt.assume_utc());
+    }
+
     None
 }