Update ocean charm module for move to C++20

[macedo22]

Proposed changes

Since partially moving to C++20, SpECTRE doesn't build on ocean, but this new module fixes this

Upgrade instructions

Code review checklist

• The code is documented and the documentation renders correctly. Run
  make doc to generate the documentation locally into BUILD_DIR/docs/html.
  Then open index.html.
• The code follows the stylistic and code quality guidelines listed in the
  code review guide.
• The PR lists upgrade instructions and is labeled bugfix or
  new feature if appropriate.

Further comments

[knelli2]

Was able to build unit tests and BBH exec on ocean with this. Ignoring unrelated test timeout