Revert "Remove deployment secret argument"

Secrets are not automatically passed to reusable workflows and need to
be passed in directly[^1].

1: https://docs.github.com/en/actions/how-tos/write-workflows/choose-what-workflows-do/use-secrets#using-secrets-in-a-workflow:~:text=Secrets%20are%20not%20automatically%20passed%20to%20reusable%20workflows%2E%20For%20more%20information%2C%20see%20Reuse%20workflows%2E

This reverts commit 14c96a9.

Author: Sparrow0hawk

.github/workflows/ci.yml

@@ -108,3 +108,5 @@ jobs:
       tag: ${{ needs.build.outputs.version }}
     # only run deploy for CI runs on main
     if: github.event_name != 'pull_request'
+    secrets:
+      GCP_CREDENTIALS_DEPLOY: ${{ secrets.GCP_CREDENTIALS_DEPLOY }}

.github/workflows/deploy.yml

@@ -14,6 +14,10 @@ on:
         type: string
         required: true
 
+    secrets:
+      GCP_CREDENTIALS_DEPLOY:
+        required: true
+
   workflow_dispatch:
     inputs:
       environment: