spdx3: software_purpose: add REQUIREMENT type

Signed-off-by: Stanislav Pankevich <s.pankevich@gmail.com>

Author: stanislaw

src/spdx_tools/spdx3/model/software/software_purpose.py

@@ -24,5 +24,6 @@ class SoftwarePurpose(Enum):
     OPERATING_SYSTEM = auto()
     OTHER = auto()
     PATCH = auto()
+    REQUIREMENT = auto()
     SOURCE = auto()
     TEST = auto()