Mark PostgreSQL package as side-effectful

The package applies Temporal polyfills at module load time, so its
package metadata must not advertise the module as side-effect free.

Set sideEffects to true so bundlers preserve the initialization when
consumers import the package.

#19 (comment)

Co-Authored-By: OpenAI Codex <codex@openai.com>

Author: dahlia

packages/botkit-postgres/package.json

@@ -35,7 +35,7 @@
     },
     "./package.json": "./package.json"
   },
-  "sideEffects": false,
+  "sideEffects": true,
   "files": [
     "dist",
     "LICENSE",