fix(android): Avoid ConcurrentModificationException

[spydon]

Description

When playing a lot of sounds simultaneously apparently some users get ConcurrentModificationException in this for loop.
The best solution would be to be able to use a ConcurrentHashMap, but I don't know how to do that in here.

Checklist

• The title of my PR starts with a Conventional Commit prefix (fix:, feat:, docs:, chore: etc).
• I have read the Contributor Guide and followed the process outlined for submitting PRs.
• I have updated/added tests for ALL new/updated/fixed functionality.
• I have updated/added relevant documentation and added dartdoc comments with ///, where necessary.
• I have updated/added relevant examples in example.

Breaking Change

• Yes, this is a breaking change.
• No, this is not a breaking change.

Related Issues

Closes #1274

[Gustl22]

I'll have a look later this week :)

[spydon]

I'll have a look later this week :)

None of my tried things worked so not much to have a look at yet 😅

[Gustl22]

@spydon I reproduced the issue reliably and with the ConcurrentMap it was fixed. Only the declaration was missing :)

[spydon]

@spydon I reproduced the issue reliably and with the ConcurrentMap it was fixed. Only the declaration was missing :)

That's awesome to hear!