Validation fails for valid input with textual months followed by period (MMM. and MMMM.)

**Describe the bug**
In our date field, formats including MMM and MMMM cause the `dayjs(value, format, strict=true).isValid()` to return false for all values.

**Expected behavior**
`IsValid()` should return true

**Information**
- Day.js Version: dayjs@^1.10.6: version "1.11.3"
- OS: Windows 10
- Browser: Chrome
- Time zone: GMT+2 - Central European Summer Time

Start by reproducing the issue with dayjs(value, format, strict=true).isValid() using formats containing MMM and MMMM followed by a period. Compare the result with the stated expectation that valid values return true; the issue does not name a source file or test to inspect.

Written by the indexing model from the issue text.