DynamoDB: Add TransactionCanceledException

[pulltab]

Purpose

TransactionCanceledException was not previously parsable, resulting in
generic AmazonDynamoDBExceptions being returned with no ability
for users to extract specifics as to why the transaction has been
canceled.

References

References #1847

Changes

• Introduced a new shape capable of parsing TransactionCanceledExceptions.

Background Context

Given this update was so trivial, I feel there was no other approach that can be justified.

TransactionCanceledException was simply not added when transaction support was originally introduced.

[lightbend-cla-validator]

At least one pull request committer is not linked to a user. See https://help.github.com/en/articles/why-are-my-commits-linked-to-the-wrong-user#commits-are-not-linked-to-any-user

[pulltab]

Note - I signed the CLA after the PR was created.

[lightbend-cla-validator]

At least one pull request committer is not linked to a user. See https://help.github.com/en/articles/why-are-my-commits-linked-to-the-wrong-user#commits-are-not-linked-to-any-user

[2m]

I have rebased this PR on top of the latest master as there were some changes in master that affected CI.

@pulltab can you add the email from the commit to your GitHub profile, so CLA checker can match GitHub user that signed CLA and the committer?

[2m]

LGTM

[pulltab]

@2m Thank you.

I added the email I used to sign the CLA to my profile. Is there anything I need to do to retrigger the check?

[2m]

I re-triggered CLA checker, but the status is still the same. Note, that you need to add the email, that you used to author the commit (you can see it here: https://github.com/akka/alpakka/commit/151d471bdb386d0c20538ae6b24fc155d8671534.patch) to your GitHub profile.

[pulltab]

Ah, yes, I meant to make the commit under my personal email.

Let me re-author the change such that it is using the proper email address.

[pulltab]

Ok. The commit has been amended.