Log Message:
pkgtools/url2pkg: update to 20.3.0

Changes since 20.2.0:

Fixed detection for V2 Cargo.lock files.  Patch provided by snow flurry
via tech-pkg, slightly adjusted.  The test case for Cargo.lock file
detection had been incomplete and unrealistic.  It has been extended to
show the relevant section of a whole package.

https://mail-index.netbsd.org/tech-pkg/2020/10/12/msg023897.html
https://mail-index.netbsd.org/tech-pkg/2020/10/13/msg023901.html
https://mail-index.netbsd.org/tech-pkg/2020/10/13/msg023902.html