Allow ciflow/binaries label to trigger wheel builds on PRs (pytorch#12505)

Following PR (pytorch#12425) broke Linux manywheel and there was no way to
repro it on that PR; I just happened to catch it because the PR after
that (pytorch#12468) triggered the manywheel build.

Author: swolchok

.github/workflows/build-wheels-linux.yml

@@ -9,6 +9,8 @@ on:
       - examples/**/*
       - pyproject.toml
       - setup.py
+    tags:
+      - ciflow/binaries/*
   push:
     branches:
       - nightly

.github/workflows/build-wheels-macos.yml

@@ -9,6 +9,8 @@ on:
       - examples/**/*
       - pyproject.toml
       - setup.py
+    tags:
+      - ciflow/binaries/*
   push:
     branches:
       - nightly