Add CUDA support for num_digits

[mborland]

No description provided.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.86%. Comparing base (af47854) to head (9d98c61).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop       #3   +/-   ##
========================================
  Coverage    94.86%   94.86%           
========================================
  Files           74       74           
  Lines         9009     9009           
========================================
  Hits          8546     8546           
  Misses         463      463           

Files with missing lines	Coverage Δ
...ude/boost/charconv/detail/integer_search_trees.hpp	99.25% <100.00%> (ø)

---

Continue to review full report in Codecov by Sentry.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update af47854...9d98c61. Read the comment docs.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.