feat: add googlepubsub bindings

Adds support for Google Cloud Pub/Sub to the `Channel Binding Object`
and `Message Binding Object` lists.

See: asyncapi/bindings#141

spec/asyncapi.md

@@ -1010,6 +1010,7 @@ Field Name | Type | Description
 <a name="channelBindingsObjectRedis"></a>`redis` | [Redis Channel Binding](https://github.com/asyncapi/bindings/blob/master/redis#channel) | Protocol-specific information for a Redis channel.
 <a name="channelBindingsObjectMercure"></a>`mercure` | [Mercure Channel Binding](https://github.com/asyncapi/bindings/blob/master/mercure#channel) | Protocol-specific information for a Mercure channel.
 <a name="channelBindingsObjectIBMMQ"></a>`ibmmq` | [IBM MQ Channel Binding](https://github.com/asyncapi/bindings/tree/master/ibmmq#channel-binding-object) | Protocol-specific information for an IBM MQ channel.
+<a name="channelBindingsObjectGooglePubSub"></a>`googlepubsub` | [Google Cloud Pub/Sub Channel Binding](https://github.com/asyncapi/bindings/tree/master/googlepubsub#channel) | Protocol-specific information for a Google Cloud Pub/Sub channel.
 
 This object MAY be extended with [Specification Extensions](#specificationExtensions).
 
@@ -1070,6 +1071,7 @@ Field Name | Type | Description
 <a name="messageBindingsObjectRedis"></a>`redis` | [Redis Message Binding](https://github.com/asyncapi/bindings/blob/master/redis#message) | Protocol-specific information for a Redis message.
 <a name="messageBindingsObjectMercure"></a>`mercure` | [Mercure Message Binding](https://github.com/asyncapi/bindings/blob/master/mercure#message) | Protocol-specific information for a Mercure message.
 <a name="messageBindingsObjectIBMMQ"></a>`ibmmq` | [IBM MQ Message Binding](https://github.com/asyncapi/bindings/tree/master/ibmmq#message-binding-object) | Protocol-specific information for an IBM MQ message.
+<a name="messageBindingsObjectGooglePubSub"></a>`googlepubsub` | [Google Cloud Pub/Sub Message Binding](https://github.com/asyncapi/bindings/tree/master/googlepubsub#message) | Protocol-specific information for a Google Cloud Pub/Sub message.
 
 This object MAY be extended with [Specification Extensions](#specificationExtensions).