chore(firestore): [PQ] update copyright year

[bhshkh]

header-check fails on #12347 with error

firestore/pipeline.go should have a copyright year of 2026
firestore/pipeline_aggregate.go should have a copyright year of 2026
firestore/pipeline_constant.go should have a copyright year of 2026
firestore/pipeline_expression.go should have a copyright year of 2026
firestore/pipeline_field.go should have a copyright year of 2026
firestore/pipeline_filter_condition.go should have a copyright year of 2026
firestore/pipeline_function.go should have a copyright year of 2026
firestore/pipeline_integration_test.go should have a copyright year of 2026
firestore/pipeline_result.go should have a copyright year of 2026
firestore/pipeline_result_test.go should have a copyright year of 2026
firestore/pipeline_source.go should have a copyright year of 2026
firestore/pipeline_source_test.go should have a copyright year of 2026
firestore/pipeline_stage.go should have a copyright year of 2026
firestore/pipeline_stage_test.go should have a copyright year of 2026
firestore/pipeline_test.go should have a copyright year of 2026
firestore/pipeline_utils.go should have a copyright year of 2026

Fixing it in this PR

[gemini-code-assist]

Summary of Changes

Hello @bhshkh, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request focuses on a routine maintenance task to ensure compliance with project standards. It updates the copyright year in several Go source files within the Firestore module, specifically those related to the pipeline functionality. This change rectifies a header-check failure, ensuring that all relevant files reflect the current copyright year.

Highlights

• Copyright Year Update: The copyright year in numerous Firestore pipeline-related Go files has been updated from 2025 to 2026.
• Header Check Compliance: This change addresses and resolves a header-check failure that was reported due to outdated copyright years in the specified files.

🧠 New Feature in Public Preview: You can now enable Memory to help Gemini Code Assist learn from your team's feedback. This makes future code reviews more consistent and personalized to your project's style. Click here to enable Memory in your admin console.

Using Gemini Code Assist

The full guide for Gemini Code Assist can be found on our documentation page, here are some quick tips.

Invoking Gemini

You can request assistance from Gemini at any point by creating a comment using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands on the current page.

Feature	Command	Description
Code Review	/gemini review	Performs a code review for the current pull request in its current state.
Pull Request Summary	/gemini summary	Provides a summary of the current pull request in its current state.
Comment	@gemini-code-assist	Responds in comments when explicitly tagged, both in pull request comments and review comments.
Help	/gemini help	Displays a list of available commands.

Customization

To customize Gemini Code Assist for GitHub experience, repository maintainers can create a configuration file and/or provide a custom code review style guide (such as PEP-8 for Python) by creating and adding files to a .gemini/ folder in the base of the repository. Detailed instructions can be found here.

Limitations & Feedback

Gemini Code Assist may make mistakes. Please leave feedback on any instances where its feedback is incorrect or counter productive. You can react with 👍 and 👎 on @gemini-code-assist comments. If you're interested in giving your feedback about your experience with Gemini Code Assist for Github and other Google products, sign up here.

You can also get AI-powered code generation, chat, as well as code reviews directly in the IDE at no cost with the Gemini Code Assist IDE Extension.

Footnotes

1. Review the Privacy Notices, Generative AI Prohibited Use Policy, Terms of Service, and learn how to configure Gemini Code Assist in GitHub here. Gemini can make mistakes, so double check it and use code with caution. ↩

[gemini-code-assist]

Code Review

This pull request consists of a series of automated updates to the copyright year in the file headers across the firestore package. The changes from 2025 to 2026 are consistent with the goal of resolving the header-check failure mentioned in the description. These are routine maintenance changes and appear to be correct.