fix(schematics): make action props plural

[michaelxvoelker]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/ngrx/platform/blob/main/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Documentation has been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[x] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Documentation content changes
[ ] Other... Please describe:

What is the current behavior?

The reducer uses the plural form for the action property of add and upsert actions, though the definitions of the actions use the singular form. This results in errors.

Originally found by @manfredsteyer in a workshop.

What is the new behavior?

add and upsert actions define their properties in plural form

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

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[timdeschryver]

Good catch, thanks!

[markostanimirovic]

Thanks @michaelxvoelker!

[michaelxvoelker]

You're welcome 🤗