Update pyminify to return the input source unchanged if it can't be m… #506

Job	Run time
Create sdist and Python 3 Wheel	36s
Test Documentation	33s
Create Python 2 Wheel	46s
Test Typing (wheel)	37s
Test Typing (sdist)	42s
Test Package (3.4, wheel)	19s
Test Package (2.7, wheel)	15s
Test Package (3.3, sdist)	23s
Test Package (3.6, wheel)	19s
Test Package (3.7, sdist)	22s
Test Package (3.8, wheel)	16s
Test Package (3.7, wheel)	20s
Test Package (3.5, wheel)	20s
Test Package (3.6, sdist)	18s
Test Package (3.12, wheel)	25s
Test Package (3.9, wheel)	24s
Test Package (2.7, sdist)	16s
Test Package (3.10, sdist)	28s
Test Package (3.10, wheel)	30s
Test Package (3.8, sdist)	17s
Test Package (3.11, wheel)	24s
Test Package (3.9, sdist)	24s
Test Package (3.4, sdist)	18s
Test Package (3.5, sdist)	19s
Test Package (3.11, sdist)	25s
Test Package (3.13, wheel)	26s
Test Package (3.12, sdist)	33s
Test Package (3.3, wheel)	23s
Test Package (3.13, sdist)	27s
	12m 5s

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