buildomat: bump target to lab-3.0-gimlet (#766)

Fixes: #764

Signed-off-by: Trey Aspelund <trey@oxidecomputer.com>

Author: taspelund

.github/buildomat/jobs/falcon-lab.sh

@@ -2,7 +2,7 @@
 #:
 #: name = "falcon"
 #: variety = "basic"
-#: target = "lab-2.0-gimlet"
+#: target = "lab-3.0-gimlet"
 #: skip_clone = true
 #: output_rules = [
 #:   "/work/*",

.github/buildomat/jobs/test-interop.sh

@@ -2,7 +2,7 @@
 #:
 #: name = "test-interop"
 #: variety = "basic"
-#: target = "lab-2.0-gimlet"
+#: target = "lab-3.0-gimlet"
 #: skip_clone = true
 #: output_rules = [
 #:   "/work/*",