Merge pull request #53685 from dtzWill/update/scons-3.0.3

scons: 3.0.2 -> 3.0.3

"This release should be used instead of 3.0.2. This release fixes
several issues. This release supports Python versions 2.7.* as well as
3.5+." [0]

Details can be found in the changelog [1].

"NOTE: 3.0.2 release was dropped because there was a packaging bug. Please
consider all 3.0.2 content."

There where no regressions and no deprecations in this release (at least it does
not break any builds in nixpkgs).

[0]: https://scons.org/scons-303-is-available.html
[1]: https://raw.githubusercontent.com/SConsProject/scons/rel_3.0.3/src/CHANGES.txt