WIP install: 7.5 and 7.6

FIXME:
- sshpassword likely did not work at the time
- only install itself is handled

tests/install/test.py

@@ -17,13 +17,15 @@
 @pytest.mark.dependency()
 class TestNested:
     @pytest.mark.parametrize("iso_version", (
-        "80", "81",
+        "75", "76", "80", "81",
         "ch821.1", "xs8",
         "821.1", "83b2",
     ))
     @pytest.mark.parametrize("firmware", ("uefi", "bios"))
     @pytest.mark.installer_iso(
         lambda version: {
+            "75": "xcpng-7.5",
+            "76": "xcpng-7.6",
             "80": "xcpng-8.0",
             "81": "xcpng-8.1",
             "821.1": "xcpng-8.2.1-2023",