fix docs.yml by installing torchmetrics (pytorch#1433)

Summary:

manually install torchmetrics.

for some reason this problem isn't countered in build-wheels-linux

Differential Revision: D50091290

.github/workflows/docs.yml

@@ -56,6 +56,9 @@ jobs:
     - name: Install fbgemm
       run: |
         conda run -n build_binary pip install fbgemm-gpu --index-url https://download.pytorch.org/whl/nightly/cpu
+    - name: Install torchmetrics
+      run: |
+        conda run -n build_binary pip install torchmetrics==1.0.3
     - name: Install TorchRec
       run: |
         conda run -n build_binary pip install torchrec --index-url https://download.pytorch.org/whl/nightly/cpu