remove_dir_all caret dependency is incompatible with tempfile MSRV

[str4d]

The recent 0.5.3 release of the remove_dir_all crate bumped its effective MSRV to 1.40.0, and as now documented in XAMPPRocky/remove_dir_all#21 (comment), the crate only supports the latest Rust version. However, the remove_dir_all crate is specified as a (default) caret dependency of tempfile:

tempfile/Cargo.toml

Line 22 in 6fe7f2c

remove_dir_all = "0.5"

This automatically selects 0.5.3, breaking tempfile's MSRV of 1.32.0.

tempfile should either pin with =0.5.2 until its MSRV reaches 1.40.0 (and always pin specific versions going forward, as caret dependencies may similarly break in future), or remove the remove_dir_all dependency.

[Stebalien]

It's about time to bump the MSRV anyways. 1.40 is 6 months old at this point.