feat: enhance input field for Intervals API Key with matInput directive

Author: costa-alex

ui/src/app/configuration/configuration.component.html

@@ -42,7 +42,7 @@ <h2 class="config-title app-panel-card-title">Intervals.icu</h2>
 
           <mat-form-field class="full-width">
             <mat-label>Intervals API Key</mat-label>
-            <input type="password" placeholder="123456qwerty123456qwerty1" formControlName="intervals.api-key">
+            <input matInput type="password" placeholder="123456qwerty123456qwerty1" formControlName="intervals.api-key">
           </mat-form-field>
 
           <mat-form-field class="full-width">