tests/bloom_bytes: define regexp as raw strings

Python strings for regular expression should be declared as `raw` so `\`
is not re-interpreted.

This fixes `flake8` warning.

tests/bloom_bytes/tests/01-run.py

@@ -16,10 +16,10 @@ TIMEOUT = 150
 def testfunc(child):
     child.expect_exact("Testing Bloom filter.")
     child.expect_exact("m: 4096 k: 8")
-    child.expect("adding 512 elements took \d+ms", timeout=TIMEOUT)
-    child.expect("checking 10000 elements took \d+ms", timeout=TIMEOUT)
-    child.expect("\d+ elements probably in the filter.")
-    child.expect("\d+ elements not in the filter.")
+    child.expect(r"adding 512 elements took \d+ms", timeout=TIMEOUT)
+    child.expect(r"checking 10000 elements took \d+ms", timeout=TIMEOUT)
+    child.expect(r"\d+ elements probably in the filter.")
+    child.expect(r"\d+ elements not in the filter.")
     child.expect(".+ false positive rate.")
     child.expect_exact("All done!")