Reuse creating SPDX with faulty information

[rettichschnidi]

Describe the bug

Running reuse spdx states that the use conanfile.py is copyrighted by the ORT Project Authors, which seem unlikely as it (seemingly) got copied from https://github.com/pocoproject/conan-poco (However, I could not find an applicable license nor copyright statements).

To Reproduce

$ reuse --suppress-deprecation spdx | grep -A5 ./plugins/package-managers/conan/src/funTest/assets/projects/synthetic/conan-py/conanfile.py
FileName: ./plugins/package-managers/conan/src/funTest/assets/projects/synthetic/conan-py/conanfile.py
SPDXID: SPDXRef-e745a5fac147cabc6de238e223d74914
FileChecksum: SHA1: b2ca53b871356c3870c9606db09c6d1aea890f5a
LicenseConcluded: NOASSERTION
LicenseInfoInFile: Apache-2.0
FileCopyrightText: <text>2017 The ORT Project Authors (see <https://github.com/oss-review-toolkit/ort/blob/main/NOTICE>)</text>

Expected behavior

Reuse should produce a SPDX file with correct license and copyright information.

Proposed fix

Adding the needed information as part of #8758 (the new recipe has a clear license and copyright statement). However, for this to actually work, #8772 has to be implemented.