Bump @types/jest from 26.0.10 to 26.0.12

Editor assessment

The subject identifies the types/jest bump with both versions and the pull request number, so the update is unambiguous, and the build type with the deps-dev scope is the correct category. No body is provided, appropriate for a routine dev dependency and free of changelog boilerplate. The header is imperative and unterminated. Clear and accurately typed; the sole shortfall is the absent rationale, which is not expected for a version bump and so does not lower the grade.