fix(metrics): Corrected dimension count in MS-SSIM error message for 3D images. (#8685)

Fixes # .

### Description

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### Types of changes
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- [x] Non-breaking change (fix or new feature that would not break
existing functionality).
- [ ] Breaking change (fix or new feature that would cause existing
functionality to change).
- [ ] New tests added to cover the changes.
- [ ] Integration tests passed locally by running `./runtests.sh -f -u
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- [ ] In-line docstrings updated.
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folder.

---------

Signed-off-by: Akshat Sinha <akshatsinhasramhardy@gmail.com>

Author: akshatsinha0

monai/metrics/regression.py

@@ -589,7 +589,7 @@ def compute_ms_ssim(
 
     if spatial_dims == 3 and dims != 5:
         raise ValueError(
-            f"y_pred should have 4 dimensions (batch, channel, height, width, depth) when using {spatial_dims}"
+            f"y_pred should have 5 dimensions (batch, channel, height, width, depth) when using {spatial_dims}"
             f" spatial dimensions, got {dims}."
         )