Lock version of OpenSearch for integration tests.

Signed-off-by: dblock <dblock@amazon.com>

Author: dblock

.github/workflows/test-integration.yml

@@ -12,7 +12,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-go@v5
-        with: { go-version-file: 'go.mod' }
+        with: { go-version-file: "go.mod" }
       - run: go version
       - name: Increase system limits
         run: |
@@ -33,10 +33,11 @@ jobs:
     runs-on: ubuntu-latest
     env:
       SECURE_INTEGRATION: true
+      OPENSEARCH_VERSION: 2.18.0
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-go@v5
-        with: { go-version-file: 'go.mod' }
+        with: { go-version-file: "go.mod" }
       - run: go version
       - name: Increase system limits
         run: |