It's very likely that you are missing one or more of:
in your spec file. The build environment starts out rather minimal and BuildRequires are used to pull in additional things. Python is rather large, so there was effort to move it from the default buildroot a little while ago.
See Dependencies in the Python section of the Fedora Packaging Guidelines.
If your program refers to
/usr/bin/python without a version number, you'll need
python-unversion-command. See this Fedora change for detail on that — in short, upstream Python has decided that
/usr/bin/python can refer to either version depending on what the user wants, which means that operating system packages should really use either
python3 explicitly. Requiring the unversioned command is an option for when you don't want to patch your program to do that for whatever reason.