Merge pull request #1008 from DLR-RM/iss1006_fix_blender_download

fix(blender): Fixes blender download

blenderproc/python/utility/InstallUtility.py

@@ -12,10 +12,10 @@
 from typing import Union, Tuple
 
 if version_info.major == 3:
-    from urllib.request import urlretrieve
+    from urllib.request import urlretrieve, build_opener, install_opener
     from urllib.error import URLError
 else:
-    from urllib import urlretrieve
+    from urllib import urlretrieve, build_opener, install_opener
     import contextlib
 
 # pylint: disable=wrong-import-position
@@ -126,6 +126,12 @@ def make_sure_blender_is_installed(custom_blender_path: str, blender_install_pat
                     url = used_url + ".zip"
                 else:
                     raise RuntimeError(f"This system is not supported yet: {platform}")
+
+                # setting the default header, else the server does not allow the download
+                opener = build_opener()
+                opener.addheaders = [('User-agent', 'Mozilla/5.0')]
+                install_opener(opener)
+
                 try:
                     try:
                         # pylint: disable=import-outside-toplevel