Make installed scripts explicitly python3

References: bsc#1077564

We want to explicitly reference python3 in the scripts we install.

Signed-off-by: Bruce Rogers <brogers@suse.com>

scripts/analyze-migration.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python3
+#!/usr/bin/python3
 #
 #  Migration Stream Analyzer
 #

scripts/vmstate-static-checker.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python3
+#!/usr/bin/python3
 #
 # Compares vmstate information stored in JSON format, obtained from
 # the -dump-vmstate QEMU command.