fix(cmd/gno/clean): allow to run `gno clean -modcache` from anywhere … #6010

Job	Run time
setup	3s
Run Main (gnodev) / Go Build / generated	6s
Run Main (gnodev) / Go Linter / lint	36s
Run Main (gnodev) / Go Test / test	57s
Run Main (gnofaucet) / Go Build / generated	10s
Run Main (gnofaucet) / Go Test / test	24s
Run Main (gnofaucet) / Go Linter / lint	30s
Run Main (gnogenesis) / Go Build / generated	11s
Run Main (gnogenesis) / Go Linter / lint	23s
Run Main (gnogenesis) / Go Test / test	31s
Run Main (gnokeykc) / Go Linter / lint	29s
Run Main (gnokeykc) / Go Build / generated	6s
Run Main (gnokeykc) / Go Test / test	38s
Run Main (gnomd) / Go Build / generated	12s
Run Main (gnomd) / Go Linter / lint	15s
Run Main (gnomigrate) / Go Build / generated	14s
Run Main (gnomd) / Go Test / test	27s
Run Main (gnomigrate) / Go Linter / lint	21s
Run Main (gnomigrate) / Go Test / test	32s
	7m 5s

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