[MINOR] Fixed tickbox syntax

[Errorific]

PR description

There's a syntax error in the PR template, the Types of changes section is missing spaces in the tickboxes. The error is reflected in this PR description

Related Issue(s)

Types of changes

• Docs change / refactoring / dependency upgrade
• [] Bug fix (non-breaking change which fixes an issue)
• [] New feature (non-breaking change which adds functionality)
• [] Breaking change (fix or feature that would cause existing functionality to change)

Release note

Prerequisites:

• I have read the CONTRIBUTING.md document and followed the guidelines there.
• I have commented my code, particularly in hard-to-understand areas
• I have opened an issue for corresponding changes to documentation (OR no doc changes required)
• I have added appropriate tests that prove my change is effective

[macfarla]

LGTM