Updated smarty to 2.6.28

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | 
| Refs tickets  | 
| License       | MIT (not sure if this is right for a vendor component update!)
| Doc PR        |