### What changes were proposed in this pull request?
We should use `check_exact=False` because the value check in `StatsTest.test_cov_corr_meta` is too strict.
### Why are the changes needed?
In some environment, the precision could be different in pandas' `DataFrame.corr` function and the test `StatsTest.test_cov_corr_meta` fails.
```
AssertionError: DataFrame.iloc[:, 0] (column name="a") are different
DataFrame.iloc[:, 0] (column name="a") values are different (14.28571 %)
[index]: [a, b, c, d, e, f, g]
[left]: [1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 0.0]
[right]: [1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 4.807406715958909e-17]
```
### Does this PR introduce _any_ user-facing change?
No.
### How was this patch tested?
Modified tests should still pass.
Closes#33179 from ueshin/issuse/SPARK-35981/corr.
Authored-by: Takuya UESHIN <ueshin@databricks.com>
Signed-off-by: Hyukjin Kwon <gurwls223@apache.org>
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