Extend test cert validity to 2049

[bmwiedemann]

Extend test cert validity to 2049
to make tests pass in 2022

Background:
As part of my work on reproducible builds for openSUSE, I check
that software still gives identical build results in the future.
The usual offset is +15 years, because that is how long I expect
some software will be used in some places.
This showed up failing tests in our package build.

See https://reproducible-builds.org/ for why this matters.

Note: I tested that i586 builds still pass tests on 2037-12-01
so are not affected by the year 2038 bug yet.

[codecov]

Codecov Report

Merging #91 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #91   +/-   ##
=======================================
  Coverage   80.84%   80.84%           
=======================================
  Files          35       35           
  Lines        3529     3529           
=======================================
  Hits         2853     2853           
  Misses        676      676

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[ethe]

LGTM, thank you!