script: fix invalid escape sequences

Python 3.12 warns on invalid escape sequences in non-raw strings:
```
  ceph-release-notes:45: SyntaxWarning: invalid escape sequence '\d'
  cpatch.py:465: SyntaxWarning: invalid escape sequence '\;'
```

In `cpatch.py`, use raw strings for the two Dockerfile RUN lines so
their find -exec ... \; keeps the literal backslash-semicolon.

Signed-off-by: Kefu Chai <k.chai@proxmox.com>