utils: ipc: mojom_libcamera_generator.py: Fix Python warning

Python 3.12 starts emitting the following warning when building libcamera:

  .../utils/ipc/generators/mojom_libcamera_generator.py:372:
  SyntaxWarning: invalid escape sequence '\.'
    if not re.match('^ipa\.[0-9A-Za-z_]+', namespace):

`r' prefix is now required before the regexp.

Signed-off-by: Milan Zamazal <mzamazal@redhat.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

utils/ipc/generators/mojom_libcamera_generator.py

@@ -369,7 +369,7 @@ def ValidateNamespace(namespace):
     if namespace == '':
         raise Exception('Must have a namespace')
 
-    if not re.match('^ipa\.[0-9A-Za-z_]+', namespace):
+    if not re.match(r'^ipa\.[0-9A-Za-z_]+', namespace):
         raise Exception('Namespace must be of the form "ipa.{pipeline_name}"')
 
 def ValidateInterfaces(interfaces):