Added Symfony workflows for serverless Flex

Author: mnocon

.github/workflows/flex-update-achived.yml

@@ -0,0 +1,10 @@
+name: Update Flex Archives
+
+on:
+    push:
+        branches:
+            - master
+
+jobs:
+    call-flex-update:
+        uses: symfony/recipes/.github/workflows/callable-flex-update-archived.yml@main

.github/workflows/flex-update.yml

@@ -0,0 +1,16 @@
+name: Update Flex endpoint
+
+on:
+    push:
+        branches:
+            - master
+
+defaults:
+    run:
+        shell: bash
+
+jobs:
+    call-flex-update:
+        uses: symfony/recipes/.github/workflows/callable-flex-update.yml@main
+        with:
+            branch: master