fix: Fix constant reference for Minitar.open #35

Job	Run time
Lint	23s
Ruby 3.1 - macos-12	31s
Ruby 3.1 - ubuntu-20.04	11s
Ruby 3.2 - macos-12	31s
Ruby head - macos-latest (optional)	18s
Ruby 3.2 - ubuntu-20.04	13s
Ruby 3.3 - macos-12	43s
Ruby 3.1 - windows-2019	1m 59s
Ruby head - ubuntu-latest (optional)	8s
Ruby 3.3 - ubuntu-20.04	19s
Ruby 3.1 - macos-13	27s
Ruby 3.2 - windows-2019	1m 57s
Ruby head - windows-latest (optional)	1m 12s
Ruby 3.1 - ubuntu-22.04	12s
Ruby 3.2 - macos-13	34s
Ruby 3.3 - windows-2019	4m 49s
Ruby jruby-head - macos-latest (optional)	1m 4s
Ruby 3.2 - ubuntu-22.04	11s
Ruby 3.3 - macos-13	45s
Ruby jruby-head - ubuntu-latest (optional)	1m 0s
Ruby mingw - windows-2019	1m 21s
Ruby 3.3 - ubuntu-22.04	24s
Ruby 3.1 - macos-14	15s
Ruby jruby-head - windows-latest (optional)	3m 10s
Ruby 3.1 - ubuntu-24.04	19s
Ruby mswin - windows-2019	1m 29s
Ruby 3.2 - macos-14	13s
Ruby truffleruby-head - macos-latest (optional)	39s
Ruby 3.2 - ubuntu-24.04	16s
Ruby ucrt - windows-2019	1m 26s
Ruby truffleruby-head - ubuntu-latest (optional)	37s
Ruby 3.3 - macos-14	39s
Ruby 3.1 - windows-2022	1m 21s
Ruby 3.3 - ubuntu-24.04	23s
Ruby truffleruby-head - windows-latest (optional)	10s
Ruby 3.2 - windows-2022	1m 40s
Ruby 3.3 - windows-2022	2m 4s
Ruby mingw - windows-2022	56s
Ruby mswin - windows-2022	1m 30s
Ruby ucrt - windows-2022	1m 54s
	38m 13s

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