fix TypeError for Python version comparison in test_fetch_sources_git

[branfosj]

#4917 missed changing this correctly. See https://github.com/easybuilders/easybuild-framework/actions/runs/15781864867/job/44489234590

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ERROR: test_fetch_sources_git (test.framework.easyblock.EasyBlockTest)
Test fetch_sources method from git repo.
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Traceback (most recent call last):
  File "/tmp/runner/68f96500815b8f9cffee903b731e08a62efea3f2/lib/python3.10/site-packages/test/framework/easyblock.py", line 1973, in test_fetch_sources_git
    if sys.version_info[0] < (3, 9):
TypeError: '<' not supported between instances of 'int' and 'tuple'

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[Micket]

lgtm