fix: add missing type parameter constraints

[Rugvip]

There's an issue with the type declarations in newer versions of TypeScript where the checking is a bit stricter. These typedefs need their type parameters constrained, or you will see the following errors:

node_modules/photoswipe/dist/types/gestures/tap-handler.d.ts:5:65 - error TS2344: Type 'T' does not satisfy the constraint 'string'.

5 export type AddPostfix<T, P> = import('../types.js').AddPostfix<T, P>;
                                                                  ~

  node_modules/photoswipe/dist/types/gestures/tap-handler.d.ts:5:24
    5 export type AddPostfix<T, P> = import('../types.js').AddPostfix<T, P>;
                             ~
    This type parameter might need an `extends string` constraint.

node_modules/photoswipe/dist/types/lightbox/lightbox.d.ts:16:77 - error TS2344: Type 'T' does not satisfy the constraint 'keyof PhotoSwipeEventsMap'.

16 export type EventCallback<T> = import('../core/eventable.js').EventCallback<T>;
                                                                               ~

  node_modules/photoswipe/dist/types/lightbox/lightbox.d.ts:16:27
    16 export type EventCallback<T> = import('../core/eventable.js').EventCallback<T>;
                                 ~
    This type parameter might need an `extends keyof PhotoSwipeEventsMap` constraint.

node_modules/photoswipe/dist/types/photoswipe.d.ts:16:76 - error TS2344: Type 'T' does not satisfy the constraint 'keyof PhotoSwipeEventsMap'.

16 export type EventCallback<T> = import('./core/eventable.js').EventCallback<T>;
                                                                              ~

  node_modules/photoswipe/dist/types/photoswipe.d.ts:16:27
    16 export type EventCallback<T> = import('./core/eventable.js').EventCallback<T>;
                                 ~
    This type parameter might need an `extends keyof PhotoSwipeEventsMap` constraint.

node_modules/photoswipe/dist/types/photoswipe.d.ts:20:78 - error TS2344: Type 'T' does not satisfy the constraint 'keyof PhotoSwipeEventsMap'.

20 export type AugmentedEvent<T> = import('./core/eventable.js').AugmentedEvent<T>;
                                                                                ~

  node_modules/photoswipe/dist/types/photoswipe.d.ts:20:28
    20 export type AugmentedEvent<T> = import('./core/eventable.js').AugmentedEvent<T>;
                                  ~
    This type parameter might need an `extends keyof PhotoSwipeEventsMap` constraint.

[dimsemenov]

Nice, thank you!