tests

Add MIX support #1749

Job	Run time
cpp-linter	1m 35s
reuse	8s
test (ubuntu-latest, minimal, 5.15.*)	3m 2s
windows	8m 19s
test (ubuntu-latest, full, 5.15.*)	1m 1s
xmllint	15s
test (ubuntu-latest, full-debug, 5.15.*)	56s
test (macos-latest, minimal, 5.15.*)	4m 16s
test (macos-latest, full, 5.15.*)	6m 31s
test (macos-latest, full-debug, 5.15.*)	6m 59s
test (ubuntu-latest, full, 5.9.*)	56s
test (ubuntu-latest, minimal, 6.0.*)	1m 54s
test (ubuntu-latest, minimal, 6..)	4m 4s
test (macos-latest, minimal, 6..)	12m 14s
	52m 10s

Provide feedback