Fix: Resolve issue with template association in Instance model

The Issue:
The Instance model in the postgresql-schema.prisma file previously had a Template field that was a single Template object, but this caused issues with the association of multiple templates to a single instance.

The Change:
This commit resolves the issue by changing the Template field to an array of Template objects. This allows for multiple templates to be associated with a single instance.

The Impact:
This change allows for more flexible use of templates in the system and resolves a previous limitation in the association of templates to instances.

Affected Files:
- prisma/postgresql-schema.prisma
- src/api/services/template.service.ts

Note: The migration folder added in the untracked files section is a result of the Prisma schema change and can be safely ignored in this commit message.

prisma/migrations/20240712155950_adjusts_in_templates_table/migration.sql

@@ -0,0 +1,2 @@
+-- DropIndex
+DROP INDEX "Template_instanceId_key";