Ensure exactly one trailing newline in rendered spec files

rust2rpm/__main__.py

@@ -584,7 +584,6 @@ def main():
     else:
         with open(spec_file, "w") as fobj:
             fobj.write(spec_contents)
-            fobj.write("\n")
         print(f'Wrote {fobj.name}')
         for fname, diff in zip(patch_files, diffs):
             if fname:

rust2rpm/generator.py

@@ -109,6 +109,9 @@ def spec_file_render(
         metadata=metadata,
         patch_file_manual=patch_file_manual,
         patch_file_automatic=patch_file_automatic,
-        **kwargs) + '\n'
+        **kwargs)
+
+    if not spec_contents.endswith("\n"):
+        spec_contents += "\n"
 
     return spec_contents