Fix three issues with code style in our test infra:
- 'print' is now a function,
- exceptions need to be caught-assigned with the 'as' keyword,
- old-style "%s"%() formatting is deprecated.
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Ricardo Martincoski <ricardo.martincoski@gmail.com>
[Thomas: drop indices in format strings.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>