add more cache-like files to .lintr exclusions

[MichaelChirico]

Discovered as part of revdep checks for upcoming CRAN release -- see https://github.com/r-lib/lintr/issues/1340.

We can avoid this altogether by simply excluding these cache-like dump scripts from linting in the first place.

[AshesITR]

NB once lintr 3.0.0 is out, the exclusions can be simplified to directly exclusions.