bitbake.conf: Add /run/ to PSEUDO_IGNORE_PATHS

Builds were failing on WSL2 which turns out to be due to accesses to
/run/ on those systems. Add this to PSEUDO_IGNORE_PATHS to fix
builds on WSL2.

[YOCTO #14175]

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>