Properly use tabs in Makefile #265

Job	Run time
format	6s
fpm-test (ubuntu-latest, gcc, 10)	24s
make-test (ubuntu-latest, gcc, 13)	38s
fpm-test (ubuntu-latest, intel, 2023.2)	1m 53s
make-test (ubuntu-latest, intel, 2023.2)	2m 3s
fpm-test (macos-latest, gcc, 10)	52s
make-test (ubuntu-latest, intel-classic, 2021.1)	2m 1s
fpm-test (windows-latest, gcc, 10)	7m 45s
fpm-test (windows-latest, intel, 2023.2)	6m 1s
make-test (ubuntu-latest, nvidia-hpc, 23.11)	5m 5s
make-test (macos-latest, gcc, 13)	1m 12s
fpm-test (ubuntu-latest, nvidia-hpc, 23.11)	3m 58s
make-test (macos-13, intel-classic, 2021.1)	1m 31s
fpm-test (ubuntu-latest, intel-classic, 2021.1)	1m 37s
	35m 6s

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