Pin conda <25.7 to fix Windows build (#5176)

Summary:

🤖 This diff was automatically generated by myclaw_faiss_monitor

conda 25.7.0 was released today and broke conda-build 25.3.1's plugin
registration. When conda 25.7.0 is installed, the `conda build` subcommand
is no longer recognized, even though conda-build is installed in the same
environment. Root cause: conda-build 25.3.1 was released before conda 25.7.0
and its plugin entry point is incompatible with conda 25.7.0's plugin loader.

Fix: change `<=25.07` to `<25.7` to exclude conda 25.7.0 until conda-build
is updated to support it.

The previous constraint `<=25.07` treated 25.07 and 25.7.0 as equivalent
(PEP 440), so conda 25.7.0 was pulled in. The new constraint `<25.7` pins
below the broken release.

Differential Revision: D103589106

Author: mdouze

.github/actions/build_conda/action.yml

@@ -33,6 +33,7 @@ runs:
         miniforge-version: latest # ensures conda-forge channel is used.
         channels: conda-forge
         conda-remove-defaults: 'true'
+        activate-environment: 'base'
         # Set to runner.arch=aarch64 if we're on arm64 because
         # there's no miniforge ARM64 package, just aarch64.
         # They are the same thing, just named differently.
@@ -43,7 +44,7 @@ runs:
       run: |
         # Ensure starting packages are from conda-forge.
         conda list --show-channel-urls
-        conda install -y -q "conda!=24.11.0,<=25.07"
+        conda install -y -q "conda!=24.11.0,<25.7"
         conda install -y -q "conda-build=25.3.1" "liblief=0.14.1"
     - name: Enable anaconda uploads
       if: inputs.label != ''

conda/faiss/meta.yaml

@@ -156,7 +156,8 @@ outputs:
       requires:
         - numpy >=2.0,<3.0
         - scipy
-        - pytorch-cpu >=2.7
+        - pytorch-cpu >=2.7  # [not win]
+        - pytorch >=2.7      # [win]
         {% if PY_VER == '3.10' or PY_VER == '3.11' %}
         - mkl >=2024.2.2  # [x86_64]
         - python_abi <3.12