fix: await ledger.melt() call in test_melt_quote_reuse_same_outputs

[vicjuma]

Description: The melt() call was wrapped in a trailing-comma tuple, which created the coroutine but never awaited it. This led to a silent no-op, meaning the test wasn't actually exercising the output-reuse scenario it claims to test.

Fixes: coroutine 'Ledger.melt' was never awaited (RuntimeWarning)

Change:

@@ -253,7 +253,7 @@ async def test_melt_quote_reuse_same_outputs(wallet, ledger: Ledger):
     change_outputs, change_rs = wallet._construct_outputs(
         n_change_outputs * [1], change_secrets, change_rs
     )
-    (ledger.melt(proofs=proofs1, quote=melt_quote1.quote, outputs=change_outputs),)
+    await ledger.melt(proofs=proofs1, quote=melt_quote1.quote, outputs=change_outputs)

Testing:

pytest tests/mint/test_mint_melt.py::test_melt_quote_reuse_same_outputs

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 74.52%. Comparing base (a935eb9) to head (57070b5).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1080      +/-   ##
==========================================
- Coverage   74.54%   74.52%   -0.02%     
==========================================
  Files         115      115              
  Lines       13195    13195              
==========================================
- Hits         9836     9834       -2     
- Misses       3359     3361       +2     

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