ci: testing: build: Try x509 keys instead of ssh authorized_keys for …

…public-keys existing x509 contents read_bytes

Asciinema: https://asciinema.org/a/627133
Signed-off-by: John Andersen <johnandersenpdx@gmail.com>

.github/workflows/testing.yml

@@ -136,7 +136,7 @@ jobs:
         # Display or save the PEM encoded certificate
         contents = b""
         try:
-            pathlib.Path("public-keys", "x509").read_bytes()
+            contents = pathlib.Path("public-keys", "x509").read_bytes()
         except:
             pass
         pathlib.Path("public-keys", "x509").write_bytes(contents + b"\n" + cert_pem)