### Rationale for this change
`python/pyarrow/array.pxi` defines the class as `Decima32Array` (missing `l`).
### What changes are included in this PR?
Renaming of the class in `array.pxi` to `Decimal32Array`.
### Are these changes tested?
I haven't added a special test for this.
### Are there any user-facing changes?
No.
### Was AI used for this PR?
**PR code and description written by:**
- [X] Human
- [ ] AI
**Reviewed before submission by:**
- [X] Human
- [ ] AI
- [ ] Not reviewed
* GitHub Issue: #55285
Authored-by: AlenkaF <frim.alenka@gmail.com>
Signed-off-by: Tadeja Kadunc <tadeja.kadunc@gmail.com>