SPDX version does not match the description

[grouigrokon]

In spdx.py line 3, the comment says:

"""Generate an SPDX file.

This is following the specification from https://spdx.github.io/spdx-spec/v2.3/
a simple example can be found at ./tests/tests_e3/spdx_test.py
"""

While the DocumentInformation class says it uses SPDX version 1.2:

@dataclass
class DocumentInformation(SPDXSection):
    """Describe the SPDX Document."""

    document_name: DocumentName
    document_namespace: DocumentNamespace = field(init=False)
    version: SPDXVersion = SPDXVersion("SPDX-1.2")

See https://spdx.github.io/spdx-spec/v2.3/document-creation-information/#61-spdx-version-field