Update ReadTheDocs config when version changes

Author: jim-easterbrook

utils/build_swig.py

@@ -204,6 +204,12 @@ def __init__(self, code, message):
 __all__ = [x for x in __all__ if x[0] != '_']
 __all__.sort()
 """)
+    # update ReadTheDocs config
+    with open('src/doc/requirements.txt', 'w') as f:
+        f.write(f'''exiv2 <= {py_exiv2_version}
+sphinx == 7.2.6
+sphinx-rtd-theme == 2.0.0
+''')
     return 0