Ruff fix.

Author: Shyue Ping Ong

pymatgen/analysis/tests/test_quasiharmonic_debye_approx.py

@@ -107,7 +107,7 @@ def setUp(self):
     def test_bulk_modulus(self):
         eos = EOS(self.eos)
         eos_fit = eos.fit(self.volumes, self.energies)
-        print(f"{str(eos_fit.b0_GPa)=}")
+        print(f"{eos_fit.b0_GPa=!s}")
         bulk_modulus = float(str(eos_fit.b0_GPa).split()[0])
         bulk_modulus_ans = float(str(self.qhda.bulk_modulus).split()[0])
         np.testing.assert_almost_equal(bulk_modulus, bulk_modulus_ans, 3)