Issue #14720: sqlite3: Convert datetime microseconds correctly

Patch by Lowe Thiderman
diff --git a/Lib/sqlite3/dbapi2.py b/Lib/sqlite3/dbapi2.py
index 6c121a5..1048992 100644
--- a/Lib/sqlite3/dbapi2.py
+++ b/Lib/sqlite3/dbapi2.py
@@ -67,7 +67,7 @@
         timepart_full = timepart.split(b".")
         hours, minutes, seconds = map(int, timepart_full[0].split(b":"))
         if len(timepart_full) == 2:
-            microseconds = int(timepart_full[1])
+            microseconds = int('{:0<6}'.format(timepart_full[1].decode()))
         else:
             microseconds = 0