[webview_flutter] Update Pigeon for Kotlin 1.8 compat

[stuartmorgan-g]

Rolls Pigeon to 26.1.2 in webview_flutter_android to pick up a fix for a Kotlin 1.8 compatibility issue.

Fixes flutter/flutter#178756

Pre-Review Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• I read the Tree Hygiene page, which explains my responsibilities.
• I read and followed the relevant style guides and ran the auto-formatter.
• I signed the CLA.
• The title of the PR starts with the name of the package surrounded by square brackets, e.g. [shared_preferences]
• I linked to at least one issue that this PR fixes in the description above.
• I updated pubspec.yaml with an appropriate new version according to the pub versioning philosophy, or I have commented below to indicate which version change exemption this PR falls under¹.
• I updated CHANGELOG.md to add a description of the change, following repository CHANGELOG style, or I have commented below to indicate which CHANGELOG exemption this PR falls under¹.
• I updated/added any relevant documentation (doc comments with ///).
• I added new tests to check the change I am making, or I have commented below to indicate which test exemption this PR falls under¹.
• All existing and new tests are passing.

Footnotes

1. Regular contributors who have demonstrated familiarity with the repository guidelines only need to comment if the PR is not auto-exempted by repo tooling. ↩ ↩² ↩³

[stuartmorgan-g]

test-exempt: rolling dependencies

[gemini-code-assist]

Code Review

This pull request correctly addresses a Kotlin 1.8 compatibility issue by updating the Pigeon dependency to version 26.1.2 in the webview_flutter_android package. The changes are well-executed, including the necessary updates to pubspec.yaml, CHANGELOG.md, and the regenerated Pigeon files. The code is clean and the changes are consistent with the PR's objective. I have no further comments; the PR is ready for merging.