diff --git a/.github/workflows/build.yaml b/.github/workflows/build.yaml
index 8c62b586..8b0d5f47 100644
--- a/.github/workflows/build.yaml
+++ b/.github/workflows/build.yaml
@@ -105,7 +105,7 @@ jobs:
         - name: Set up Python
           uses: actions/setup-python@v4
           with:
-            python-version: ${{ matrix.python-version }}
+            python-version: 3.9
         - name: Install Poetry
           run: |
             curl -sSL https://install.python-poetry.org | python3 -
diff --git a/poetry.lock b/poetry.lock
index a2924ec8..cfbde703 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -1598,4 +1598,4 @@ testing = ["coverage (>=5.0.3)", "zope.event", "zope.testing"]
 [metadata]
 lock-version = "2.0"
 python-versions = "^3.9"
-content-hash = "719788c9100f023440bb51d5dde9c01b18cd8befd3c23e2bc6c82176d21a84a9"
+content-hash = "1e028c32bc10a514ce2b6a7ec20f78227147584e3c5c90702312c55d07429f25"
diff --git a/pyproject.toml b/pyproject.toml
index dcd32e1a..f58f0f65 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -19,7 +19,7 @@ base64io = "^1.0.3"
 sphinx-rtd-theme = "^1.2.2"
 tzlocal = "5.1"
 pytz = "^2023.3"
-PyYAML = "^6.0.1"
+PyYAML = "5.4.1"
 [tool.poetry.group.test.dependencies]
 jinja2 = "^3.1.2"
 boto3 = "^1.28.12"