Fix: install braindecode from git (1.5 not yet on PyPI)

requirements.txt

@@ -1,4 +1,6 @@
-braindecode>=1.5
+# braindecode 1.5 is dev-only on PyPI; install from git so the Space
+# matches what we develop against locally.
+braindecode @ git+https://github.com/braindecode/braindecode.git@master
 torch>=2.0
 torchinfo>=1.8
 gradio>=4.44