Function names with dashes aren't supported

When using it on a function with dashes in its name, I'm getting a Cloudformation error on deploy:
```
Error:
The CloudFormation template is invalid: Template format error: Resource name Calculate-session-metricsEventSourceMappingSQSCalculateSessionMetricsQueue is non alphanumeric.
```

The function configuration is:
```
calculate-session-metrics:
timeout: 900
maximumEventAge: 1800
handler: ...
events:
- snsSqs:
name: CalculateSessionMetrics
topicArn: ${self:custom.eventsTopicArn}
omitPhysicalId: true
maxRetryCount: 3
deadLetterQueueEnabled: true
visibilityTimeout: 1800
filterPolicy:
name:
- ....
```

I think https://github.com/agiledigital/serverless-sns-sqs-lambda/pull/813 fixes it, but figured it's best to open an issue too