This is a small d2lbook version release with the following updates:
- ENH: Add Cambridge latex style for pdf builds (#56)
- ENH: Distinguish code blocks (#58)
- STY: Fix alias and saved methods gap (dad1f4e)
- BLD: Remove nbformat and nbconvert direct dependency (#60)
- BLD: Replace mu-notedown with d2l-notedown dependency (a345928)
