GODRIVER-3098 Drop support for MongoDB 3.6

[matthewdale]

GODRIVER-3098

Summary

Drop support for MongoDB 3.6. The minimum supported MongoDB version is now 4.0.

Background & Motivation

MongoDB 3.6 reached end-of-life in 2021.

Part of a stack of changes that must be reviewed in order:

1. GODRIVER-3445 Move all logic for skipping spec tests by description into one place. #1985
2. GODRIVER-3098 Sync SDAM spec tests at 348d2f39. #1986
3. GODRIVER-3098 Drop support for MongoDB 3.6 #1988 (this PR)

[mongodb-drivers-pr-bot]

API Change Report

No changes found!

Pull Request Overview

This pull request drops support for MongoDB 3.6 by raising the minimum supported version to 4.0. Key changes include updating test skip logic, revising version checks and comments in various options and driver utilities, and updating evergreen configurations and documentation accordingly.

Reviewed Changes

Copilot reviewed 249 out of 249 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
internal/spectest/skip.go	New file containing a skip map for tests with updated reasons tailored for MongoDB 4.0+
internal/integration/unified_spec_test.go	Removed obsolete skip logic and added a call to spectest.CheckSkip
internal/integration/unified_spec_runner.go	Removed the legacy skippedTests map to rely solely on the new skip mechanism
internal/driverutil/description.go	Updated the minimum wire version from 6 to 7 to match the new driver requirements
README.md	Updated the supported MongoDB version from “3.6 and higher” to “4.0 and higher”
internal/serverselector/server_selector_test.go	Simplified test naming by removing unnecessary filename manipulation
internal/integration/causal_consistency_test.go	Removed tests specific to unsupported causal consistency behavior in legacy deployments
.evergreen/config.yml	Removed configurations for MongoDB 3.6 and retained only the setups for version 4.0
bson/bson_corpus_spec_test.go	Minor updates to test naming and test run invocation structure
internal/integration/index_view_test.go	Removed an outdated version check block for index specifications
mongo/options/*	Multiple options files: updated comments to remove outdated server version restrictions
mongo/bulk_write_models.go	Refactored SetHint comments to reflect updated version support requirements
mongo/database.go	Updated Aggregate method documentation to remove obsolete version constraints

Comments suppressed due to low confidence (1)

internal/driverutil/description.go:24

• Ensure that updating MinWireVersion from 6 to 7 is compatible with all version‐dependent logic in the driver to prevent any unintended behavior with server compatibility.

MinWireVersion = 7

The merge-base changed after approval.