Update Elastic.Transport to 0.5.7

[flobernd]

Fixes PostData.MultiJson not working correctly when DisableDirectStreaming is used.

[github-actions]

The backport to 8.17 failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-8.17 8.17
# Navigate to the new working tree
cd .worktrees/backport-8.17
# Create a new branch
git switch --create backport-8433-to-8.17
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick --mainline 1 f9426a41af01ae2be3ff818978fc440adfd812ea
# Push it to GitHub
git push --set-upstream origin backport-8433-to-8.17
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-8.17

Then, create a pull request where the base branch is 8.17 and the compare/head branch is backport-8433-to-8.17.

[github-actions]

The backport to 8.17 failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-8.17 8.17
# Navigate to the new working tree
cd .worktrees/backport-8.17
# Create a new branch
git switch --create backport-8433-to-8.17
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick --mainline 1 f9426a41af01ae2be3ff818978fc440adfd812ea
# Push it to GitHub
git push --set-upstream origin backport-8433-to-8.17
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-8.17

Then, create a pull request where the base branch is 8.17 and the compare/head branch is backport-8433-to-8.17.