Pin litellm to 1.75.3

Related to lightspeed-core#370
A workaround for BerriAI/litellm#13447 (workaround for ogx-ai/ogx#3072)

Signed-off-by: Eran Cohen <eranco@redhat.com>

Author: eranco74

test.containerfile

@@ -22,7 +22,7 @@ RUN uv venv && \
     opentelemetry-exporter-otlp \
     opentelemetry-instrumentation \
     aiosqlite \
-    litellm \
+    litellm[proxy]==1.75.3 \
     uvicorn \
     blobfile \
     datasets \