fix: update conformance stub to reflect weaver-spec v0.2.0 published state

weaver-spec is published (v0.2.0) but weaver_contracts.conformance
does not yet exist (dgenio/weaver-spec#4 still open). Update:
- Echo messages: spec IS published; runner specifically is not yet available
- pip install comment: use git+https install path (not bare package name;
  not on PyPI) and correct distribution name weaver_contracts (underscore)
- Remove now-redundant hyphen/underscore clarifying comment (replaced
  by the git+https install path which sidesteps the naming ambiguity)

Author: dgenio

.github/workflows/ci.yml

@@ -64,12 +64,12 @@ jobs:
       - name: Install dependencies
         run: pip install -e ".[dev]"
 
-      # Placeholder: activate once dgenio/weaver-spec#4 ships the conformance suite.
+      # Placeholder: activate once dgenio/weaver-spec#4 ships the conformance runner.
+      # weaver-spec IS published (v0.2.0); weaver_contracts.conformance does not yet exist.
       # Replace this step with:
-      #   pip install weaver-contracts
-      #   # Distribution name uses a hyphen; the Python module uses an underscore.
+      #   pip install git+https://github.com/dgenio/weaver-spec.git#subdirectory=contracts/python
       #   python -m weaver_contracts.conformance --target agent_kernel
       - name: weaver-spec conformance suite (stub)
         run: |
-          echo "weaver-spec conformance suite not yet published (dgenio/weaver-spec#4)."
-          echo "Stub passes. Activate when weaver_contracts.conformance is available."
+          echo "weaver-spec v0.2.0 is published; weaver_contracts.conformance runner not yet available (dgenio/weaver-spec#4)."
+          echo "Stub passes. Activate when dgenio/weaver-spec#4 ships."