Merge release/2.6 into master

[mongodb-drivers-pr-bot]

Merge new changes from release/2.6 into master.

Commits

• GODRIVER-3924 Fix bug of unmarshaling null. (GODRIVER-3924 Fix bug of unmarshaling null. #2401): 6019145

Resolving conflicts

To resolve any conflicts, check out the temporary branch and run the following command:

git merge master -m "Resolve conflicts in master"

Ignoring changes

To ignore from the remote branch, first reset the temporary branch to master and manually merge using the `ours` merge strategy:

git reset --hard master
git merge --strategy=ours release/2.6 -m "Ignore changes from release/2.6"

Then, push the temporary branch to upate the pull request.

[mongodb-drivers-pr-bot]

API Change Report

No changes found!

[mongodb-drivers-pr-bot]

🧪 Performance Results

Commit SHA: d7797dc

The following benchmark tests for version 6a208e817dd8a10007287189 had statistically significant changes (i.e., |z-score| > 1.96):

Benchmark	Measurement	% Change	Patch Value	Stable Region	H-Score	Z-Score
BenchmarkSingleFindOneByID	ops_per_second_min	-71.1564	359.6860	Avg: 1247.0223 Med: 1247.1689 Stdev: 181.8794	0.8921	-4.8787
BenchmarkSmallDocInsertOne	total_time_seconds	-4.1854	1.1337	Avg: 1.1833 Med: 1.1842 Stdev: 0.0248	0.7360	-2.0004
BenchmarkBSONFlatDocumentDecoding	total_time_seconds	-1.3743	1.1831	Avg: 1.1995 Med: 1.1992 Stdev: 0.0064	0.7965	-2.5764
BenchmarkSingleFindOneByID	allocated_bytes_per_op	-0.1084	22475.0000	Avg: 22499.4000 Med: 22503.0000 Stdev: 5.9414	0.8852	-4.1068

For a comprehensive view of all microbenchmark results for this PR's commit, please check out the Evergreen perf task for this patch.