tests/vm: avoid invalid escape in Python string

This is an error in Python 3.12; fix it by using a raw string literal
or by double-escaping the backslash.

Cc: qemu-stable@nongnu.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

tests/vm/basevm.py

@@ -331,8 +331,8 @@ def console_init(self, timeout = None):
     def console_log(self, text):
         for line in re.split("[\r\n]", text):
             # filter out terminal escape sequences
-            line = re.sub("\x1b\[[0-9;?]*[a-zA-Z]", "", line)
-            line = re.sub("\x1b\([0-9;?]*[a-zA-Z]", "", line)
+            line = re.sub("\x1b\\[[0-9;?]*[a-zA-Z]", "", line)
+            line = re.sub("\x1b\\([0-9;?]*[a-zA-Z]", "", line)
             # replace unprintable chars
             line = re.sub("\x1b", "<esc>", line)
             line = re.sub("[\x00-\x1f]", ".", line)
@@ -530,7 +530,7 @@ def get_qemu_version(qemu_path):
        and return the major number."""
     output = subprocess.check_output([qemu_path, '--version'])
     version_line = output.decode("utf-8")
-    version_num = re.split(' |\(', version_line)[3].split('.')[0]
+    version_num = re.split(r' |\(', version_line)[3].split('.')[0]
     return int(version_num)
 
 def parse_config(config, args):