spend: warn when overpaying fee #1661

Job	Run time
linter_gui	3m 29s
linter	30s
unit_tests (1.63, ubuntu-latest)	3m 5s
unit_tests (1.63, macOS-latest)	7m 48s
unit_tests (1.63, windows-latest)	4m 15s
unit_tests (nightly, ubuntu-latest)	52s
unit_tests (nightly, macOS-latest)	1m 19s
unit_tests (nightly, windows-latest)	1m 52s
unit_tests_gui (1.65, ubuntu-latest)	4m 34s
unit_tests_gui (1.65, macOS-latest)	6m 28s
unit_tests_gui (1.65, windows-latest)	7m 22s
unit_tests_gui (nightly, ubuntu-latest)	2m 32s
unit_tests_gui (nightly, macOS-latest)	3m 22s
unit_tests_gui (nightly, windows-latest)	4m 4s
	51m 32s

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