refactor: Update convergence messages for APGD and PGD solvers. #61

Job	Run time
cppcheck	1m 36s
pre-commit	2m 30s
macos-mamba	6m 58s
linux-mamba (gcc-9, gcc, gcc-9 g++-9, gcc-9, g++-9)	6m 30s
linux-mamba (gcc-11, gcc, gcc-11 g++-11, gcc-11, g++-11)	7m 3s
linux-mamba (gcc-12, gcc, gcc-12 g++-12, gcc-12, g++-12)	8m 33s
linux-mamba (clang-11, clang, clang-11, clang-11, clang++-11)	8m 54s
linux-mamba (clang-12, clang, clang-12, clang-12, clang++-12)	9m 34s
linux-mamba (clang-13, clang, clang-13, clang-13, clang++-13)	8m 42s
linux-mamba (clang-14, clang, clang-14, clang-14, clang++-14)	8m 12s
linux-mamba (clang-15, clang, clang-15, clang-15, clang++-15)	8m 9s
	1h 16m 41s

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