[Fix] `nvm_get_arch`: proper value for alpine linux #1125

Job	Run time
shellcheck_matrix (bash, nvm.sh)	44s
shellcheck_matrix (sh, nvm.sh)	44s
shellcheck_matrix (dash, nvm.sh)	41s
shellcheck_matrix (ksh, nvm.sh)	46s
shellcheck_matrix (bash, install.sh)	31s
shellcheck_matrix (bash, bash_completion)	25s
shellcheck_matrix (bash, nvm-exec)	29s
shellcheck	7s
	4m 27s

Provide feedback