argument should be pointer-like to avoid allocations (SA6002)

[vbanos]

I check the code using https://staticcheck.dev/ and I get the following warning:

pkg/spooledtempfile/spooled.go:212:20: argument should be pointer-like to avoid allocations (SA6002)
pkg/spooledtempfile/spooled.go:240:20: argument should be pointer-like to avoid allocations (SA6002)
pkg/spooledtempfile/spooled.go:258:20: argument should be pointer-like to avoid allocations (SA6002)

https://staticcheck.dev/docs/checks/#SA6002

All warnings are about the same code: spooledPool.Put(s.buf[:0])

Since spooledtempfile is a critical library, we should fix this.