chore(git): Lengthen commit summary length

[tesuji]

The default is 50, which is too short. github wrap around commit summary as 72 chars. And more blogs suggest that:

• https://matklad.github.io/2023/12/31/git-things.html#Git-Things
• https://news.ycombinator.com/item?id=38831630
• https://www.kernel.org/doc/html/v4.10/process/submitting-patches.html#the-canonical-patch-format

Bitten by the commit lint with a35f03eb62167ab370e8deb9f99814ed3dc44582 in #5547.

[epage]

I'd prefer to keep this as default. The discussion should instead be on committed for the defaults