rzSliderTplUrl should be marked as optional.

[mickdelaney]

Steps to reproduce

1. Turn on strict Component Bindings
   $compileProvider.strictComponentBindingsEnabled(true);
2. Render an rzslider without setting the rzSliderTplUrl

<rzslider
   rz-slider-model="$ctrl.sliderModel"
   rz-slider-options="$ctrl.sliderOptions">
</rzslider>

Error: [$compile:missingattr] Attribute 'rzSliderTplUrl' of 'rzslider' is non-optional and must be set!
https://errors.angularjs.org/1.7.5/$compile/missingattr?p0=rzSliderTplUrl&p1=rzslider
at angular.js:138
at strictBindingsCheck (angular.js:11243)
at initializeBinding (angular.js:11266)
at forEach (angular.js:395)
at initializeDirectiveBindings (angular.js:11255)
at nodeLinkFn (angular.js:10472)
at angular.js:10900
at processQueue (angular.js:17914)
at angular.js:17962
at Scope.$digest (angular.js:19075)

Expected behaviour

Tell us what should happen
Given the value is actually optional (there's a default value of 'rzSliderTpl.html'
It should be marked as @? (optional)

Actual behaviour

Its not optional

[ValentinH]

Hi, I didn't know about strictComponentBindingsEnabled. Would you like to submit a PR fixing this?

[mickdelaney]

Ok, leave it me with.