Tests

Fix depwarn due to wrapping `Vararg` directly in `UnionAll` #1505

Job	Run time
Tests (1, Extended) / Tests - Extended	14m 33s
Tests (1, Downstream) / Tests - Downstream	21m 8s
Tests (1, Extensions) / Tests - Extensions	34m 36s
Tests (1, Initialization) / Tests - Initialization	25m 31s
Tests (1, InterfaceI) / Tests - InterfaceI	36m 19s
Tests (1, InterfaceII) / Tests - InterfaceII	34m 55s
Tests (1, RegressionI) / Tests - RegressionI	11m 5s
Tests (lts, Downstream) / Tests - Downstream	13m 40s
Tests (1, FMI) / Tests - FMI	20m 28s
Tests (1, SymbolicIndexingInterface) / Tests - SymbolicIndexingInterface	15m 29s
Tests (lts, Extended) / Tests - Extended	9m 12s
Tests (lts, Extensions) / Tests - Extensions	23m 39s
Tests (lts, Initialization) / Tests - Initialization	17m 20s
Tests (lts, FMI) / Tests - FMI	15m 18s
Tests (lts, InterfaceI) / Tests - InterfaceI	28m 7s
Tests (lts, RegressionI) / Tests - RegressionI	8m 24s
Tests (lts, SymbolicIndexingInterface) / Tests - SymbolicIndexingInterface	9m 42s
Tests (pre, Downstream) / Tests - Downstream	20m 26s
Tests (lts, InterfaceII) / Tests - InterfaceII	33m 48s
Tests (pre, Extended) / Tests - Extended	14m 5s
Tests (pre, Extensions) / Tests - Extensions	34m 16s
Tests (pre, FMI) / Tests - FMI	20m 59s
Tests (pre, Initialization) / Tests - Initialization	24m 37s
Tests (pre, InterfaceI) / Tests - InterfaceI	35m 19s
Tests (pre, InterfaceII) / Tests - InterfaceII	35m 18s
Tests (pre, RegressionI) / Tests - RegressionI	10m 54s
Tests (pre, SymbolicIndexingInterface) / Tests - SymbolicIndexingInterface	15m 54s
	9h 45m 2s

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