Fix precision error for datetime

[Deep1998]

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 54.30%. Comparing base (5b0c2cd) to head (10ff31f).
Report is 16 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #2106      +/-   ##
============================================
+ Coverage     46.38%   54.30%   +7.92%     
+ Complexity     3940     1554    -2386     
============================================
  Files           864      396     -468     
  Lines         51358    21472   -29886     
  Branches       5394     2141    -3253     
============================================
- Hits          23823    11661   -12162     
+ Misses        25823     9120   -16703     
+ Partials       1712      691    -1021     

Components	Coverage Δ
spanner-templates	69.69% <100.00%> (+1.38%)	⬆️
spanner-import-export	∅ <ø> (∅)
spanner-live-forward-migration	76.68% <100.00%> (+0.01%)	⬆️
spanner-live-reverse-replication	77.95% <100.00%> (+0.01%)	⬆️
spanner-bulk-migration	87.43% <100.00%> (+0.04%)	⬆️

Files with missing lines	Coverage Δ
...er/migrations/avro/GenericRecordTypeConvertor.java	93.65% <100.00%> (+0.07%)	⬆️

... and 488 files with indirect coverage changes

[Deep1998]

bulk templates ITs have succeeded, merging since this change is not touched by any other template and other failures are due to quota issues.