community/diff-pdf: upgrade to 0.4.1

* Use the latest release instead of building a specific git commit
* Don't provide a dummy check, upstream doesn't have a test suite
  and simply invoking the program with --help is not a proper test
* Use SPDX identifier in $license
7 jobs for !9273 with diff-pdf-0.4.1 in 3 minutes and 2 seconds
latest detached
Status Job ID Name Coverage
  Lint
passed #144492
docker-alpine x86_64
lint

00:00:26

 
  Build
passed #144497
docker-alpine ci-build aarch64
build-aarch64

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passed #144498
docker-alpine ci-build armv7
build-armv7

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passed #144496
docker-alpine ci-build ppc64le
build-ppc64le

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passed #144495
docker-alpine ci-build s390x
build-s390x

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passed #144494
docker-alpine ci-build x86
build-x86

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passed #144493
docker-alpine ci-build x86_64
build-x86_64

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