Fix GEPAFeedbackMetric Protocol missing 'self' parameter

[Copilot]

📝 Changes Description

The GEPAFeedbackMetric and PredictorFeedbackFn Protocol classes were missing the self parameter in their __call__ methods, causing type checker errors when users implement conforming metric functions:

error: Argument of type "(gold: ..., pred: ..., ...) -> float" cannot be assigned to parameter "metric" of type "GEPAFeedbackMetric"
    "FunctionType" is incompatible with protocol "GEPAFeedbackMetric"
      Could not bind method "__call__" because "FunctionType" is not assignable to parameter "gold"

Changes:

• Added self as first parameter to GEPAFeedbackMetric.__call__ in dspy/teleprompt/gepa/gepa.py
• Added self as first parameter to PredictorFeedbackFn.__call__ in dspy/teleprompt/gepa/gepa_utils.py

✅ Contributor Checklist

• Pre-Commit checks are passing (locally and remotely)
• Title of your PR / MR corresponds to the required format
• Commit message follows required format {label}(dspy): {message}

⚠️ Warnings

None.

Original prompt

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This section details on the original issue you should resolve

<issue_title>[Bug] GEPAFeedbackMetric Protocol missing 'self' parameter causes type checker errors</issue_title>
<issue_description>### What happened?

I am getting unexpected type checker errors for my GEPA objective functions:

voss@porkpie [~] uv run pyright repro.py
/Users/voss/sources/dspy-bug/repro.py
  /Users/voss/sources/dspy-bug/repro.py:9:12 - error: Argument of type "(gold: Unknown, pred: Unknown, trace: Unknown | None = None, pred_name: Unknown | None = None, pred_trace: Unknown | None = None) -> float" cannot be assigned to parameter "metric" of type "GEPAFeedbackMetric" in function "__init__"
    "FunctionType" is incompatible with protocol "GEPAFeedbackMetric"
      Could not bind method "__call__" because "FunctionType" is not assignable to parameter "gold"
        "FunctionType" is not assignable to "Example" (reportArgumentType)
1 error, 0 warnings, 0 informations

I believe that my function is correct, and the the error reported here is a false positive. Test file is below.

Steps to reproduce

View this test file in vscode, or run the type checker as shown above: repro.py.

Note that the problem does not occur for version 3.0.4. Sadly the reason for this is not that the problem has been fixed, but instead the new @experimental(version="3.0.0") decorator on GEPAFeedbackMetric (file "teleprompt/gepa/gepa.py") confuses the type checker.

DSPy version

3.0.3</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes [Bug] GEPAFeedbackMetric Protocol missing 'self' parameter causes type checker errors #9079

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[TomeHirata]

LGTM