Fix umami analytics script name (#860)

Apparently umami renamed their script which silently broke the feature
in hugo-coder.

closes #859

### Prerequisites

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- [x] This pull request fixes a bug.
- [ ] This pull request adds a feature.
- [ ] This pull request introduces breaking change.

### Description

It fixes the umami analytics feature.

### Issues Resolved

#859 

### Checklist

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#### General

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- [x] Explain why and how the changes were necessary and implemented
respectively
- [x] Reference issue with `#<ISSUE_NO>` if applicable

#### Contributors

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