Bump gradio to 5.x to satisfy fastapi 0.115 pin

gradio 4.43 caps fastapi<0.113 which conflicts with the 0.115.5 pin
required elsewhere; gradio 5 drops that cap. The demo only uses Blocks,
Markdown, Button, State, Row, themes.Soft, and mount_gradio_app, which
are all present and stable in v5.

Made-with: Cursor

pyproject.toml

@@ -14,7 +14,7 @@ dependencies = [
     "httpx>=0.28.1,<0.29",
     "openenv-core>=0.2.0",
     "pyyaml==6.0.2",
-    "gradio>=4.40,<5",
+    "gradio>=5.0,<6",
 ]
 
 [project.optional-dependencies]

requirements.txt

@@ -5,4 +5,4 @@ requests==2.32.3
 httpx>=0.28.1,<0.29
 openenv-core>=0.2.0
 pyyaml==6.0.2
-gradio>=4.40,<5
+gradio>=5.0,<6