Bump io.openapiprocessor:build-plugins from 2025.12 to 2026.1

Bumps io.openapiprocessor:build-plugins from 2025.12 to 2026.1.

---
updated-dependencies:
- dependency-name: io.openapiprocessor:build-plugins
  dependency-version: '2026.1'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

gradle/libs.versions.toml

@@ -4,7 +4,7 @@ processor = "2025.1-SNAPSHOT"
 kotlin = "2.2.21"
 target-jdk = "11"
 build-jdk = "17"
-build-plugins = "2025.12"
+build-plugins = "2026.1"
 
 api = "2024.2"
 parser = "2025.6-SNAPSHOT"