Upgrade to `opentelemetry_sdk` 0.32.1 to address vulnerability

https://github.com/spinframework/spin/pull/3595 required updating spin-timer's Cargo.lock file, which bumped opentelemetry_sdk's version, which caused the "Review new dependencies for known vulnerabilities" CI check to fail due to https://github.com/advisories/GHSA-w9wp-h8wv-79jx.

That's technically a false positive since both the old and new versions of that dep are vulnerable, and the version bump was done in the top level Cargo.toml a month ago. In any case it needs to be addressed, but since it's unrelated to the PR, I'm going to disable the check temporarily with a comment to re-enable it once this issue has been addressed.

FWIW, I took a stab at addressing it myself, but it turned into a rabbit hole, so I had to punt.

Start with the top-level Cargo.toml and the spin-timer Cargo.lock changes described in the issue, then inspect the "Review new dependencies for known vulnerabilities" CI check and advisory GHSA-w9wp-h8wv-79jx. Determine how to update opentelemetry_sdk to 0.32.1 without leaving the check falsely failing, and re-enable the temporarily disabled check once it passes.