chore: remove pg 18 due repmgr compatbility

Author: semoal

.github/workflows/ci.yaml

@@ -123,36 +123,6 @@ jobs:
             flyio/postgres-flex-timescaledb:17
             flyio/postgres-flex-timescaledb:17.6
 
-      -
-        name: Build and push Postgres 18
-        id: docker_build_18
-        uses: docker/build-push-action@v6
-        with:
-          build-args: |
-            PG_VERSION=18.0
-            PG_MAJOR_VERSION=18
-            VERSION=${{ steps.get-latest-tag.outputs.tag }}
-          context: .
-          file: ./pg18/Dockerfile
-          push: true
-          tags: |
-            flyio/postgres-flex:18
-            flyio/postgres-flex:18.0
-      -
-        name: Build and push Postgres 18 Timescale DB
-        id: docker_build_18_timescaledb
-        uses: docker/build-push-action@v6
-        with:
-          build-args: |
-            PG_VERSION=18.0
-            PG_MAJOR_VERSION=18
-            VERSION=${{ steps.get-latest-tag.outputs.tag }}
-          context: .
-          file: ./pg18/Dockerfile-timescaledb
-          push: true
-          tags: |
-            flyio/postgres-flex-timescaledb:18
-            flyio/postgres-flex-timescaledb:18.0
 
       -
         name: Postgres 15 Image digest
@@ -172,9 +142,3 @@ jobs:
       -
         name: Postgres 17 TimescaleDB Image digest
         run: echo ${{ steps.docker_build_17_timescaledb.outputs.digest }}
-      -
-        name: Postgres 18 Image digest
-        run: echo ${{ steps.docker_build_18.outputs.digest }}
-      -
-        name: Postgres 18 TimescaleDB Image digest
-        run: echo ${{ steps.docker_build_18_timescaledb.outputs.digest }}