Fix Bugzilla 20870 - std.outbuffer.printf is trusted

[ntrel]

No description provided.

[dlang-bot]

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Bugzilla references

Auto-close	Bugzilla	Severity	Description
✓	20870	enhancement	std.outbuffer.printf is trusted

Testing this PR locally

If you don't have a local development environment setup, you can use Digger to test this PR:

dub run digger -- build "master + phobos#9037"

[ntrel]

Unrelated buildkite: style failing on std.range and ldc failing on CMake.