Incorrect casing in spanish

**Describe the bug**
when using the dayjs/locale/es, months are being displayed lowercased, this is wrong, month names must be Uppercase since they are names.
**Expected behavior**
month names shown in uppercase

**Information**
- Day.js Version 1.11.10
- OS: WSL
- Browser: Edge
- Time zone: irrelevant

Start by reproducing the reported month formatting behavior with the dayjs/locale/es locale. Inspect the locale implementation and verify the expected casing for month names. Done means the Spanish month output matches the issue's stated expectation without regressing other locale behavior.

Written by the indexing model from the issue text.