regression parsing table aliases in 0.31.0

[alamb]

sqlparser-rs 0.30.0 can parse this query

SELECT a, b, c FROM lineitem AS l (A, B, C)

However, in 0.31.0 it fails like:

ParserError("Expected identifier, found: ,")

There sadly seems to have been no regression test coverage.

I suspect it was introduced as part of c35dcc9 / #769 from @mskrzypkows

I have a local test and am working on fixing it.

This was found by one of datafusion's regression tests while we were upgrading: apache/datafusion#5457