Create /.cntr/pid file with 0644 permissions

[pranaysashank]

With the default 0600 permissions, cntr exec inside nix sandbox fails with the following error:

[nixbld@localhost:/var/lib/cntr/build/hello-2.12.1]$ cntr exec "$SHELL"
failed to open /.cntr/pid, Permission denied (os error 13)

[usertam]

I tried to work around this by using the --effective-user switch, also doesn't work:

# cntr attach --effective-user root -t command cntr-/nix/store/fhnsyfci26z3382l3gm209l0hwb44rxa-firecracker-1.10.1
thread 'main' panicked at /build/cntr-1.5.4-vendor.tar.gz/clap_builder/src/parser/error.rs:32:9:
Mismatch between definition and access of `effective-user`. Could not downcast to TypeId(0xb98b1b7157a6417863eb502cd6cb5d6d), need to downcast to TypeId(0xa85a74628ddea0610b6bc322b7fe2016)

# cntr attach --effective-user=0 -t command cntr-/nix/store/fhnsyfci26z3382l3gm209l0hwb44rxa-firecracker-1.10.1
thread 'main' panicked at /build/cntr-1.5.4-vendor.tar.gz/clap_builder/src/parser/error.rs:32:9:
Mismatch between definition and access of `effective-user`. Could not downcast to TypeId(0xb98b1b7157a6417863eb502cd6cb5d6d), need to downcast to TypeId(0xa85a74628ddea0610b6bc322b7fe2016)

[Mic92]

Sorry. Missed that one.

[usertam]

Thanks for the fix!