flask-cors: Remove minimum version pinning.

The build was failing with

```
ContextualVersionConflict(flask-cors 0.0.1
... Requirement.parse('flask-cors>=3.0.9'), {'gn3'})
```

1 files changed, 1 insertions, 1 deletions

diff --git a/setup.py b/setup.py
index 5689c1a..52662a4 100755
--- a/setup.py
+++ b/setup.py
@@ -26,7 +26,7 @@ setup(author='Bonface M. K.',
           "scipy>=1.6.0",
           "plotly>=4.14.3",
           "pyld",
-          "flask-cors>=3.0.9",
+          "flask-cors", # with the `>=3.0.9` specification, it breaks the build
           # "xapian-bindings" # this line breaks `guix shell …` for some reason
       ],
       include_package_data=True,