Pin PyYAML version to 5.3.1 to avoid CI errors temporarily (#36091)

CPython 3.0 was released recently which appears to have introduced a regression that leads to failures when installing PyYAML (and perhaps other packages too). This is a temporary fix and this commits needs to be reverted when a proper fix is available.

CHANGELOG-developer.next.asciidoc

@@ -162,6 +162,7 @@ The list below covers the major changes between 7.0.0-rc2 and main only.
 - Add benchmarking to HTTPJSON input testing. {pull}35138[35138]
 - Allow non-AWS endpoints for testing Filebeat awss3 input. {issue}35496[35496] {pull}35520[35520]
 - Add AUTH (username) and SSL/TLS support for Redis module {pull}35240[35240]
+- Pin PyYAML version to 5.3.1 to avoid CI errors temporarily {pull}36091[36091]
 
 ==== Deprecated
 

libbeat/tests/system/requirements.txt

@@ -36,7 +36,7 @@ pyrsistent==0.16.0
 pytest==7.3.2
 pytest-rerunfailures==9.1.1
 pytest-timeout==1.4.2
-PyYAML==5.4.1
+PyYAML==5.3.1
 redis==4.4.4
 requests==2.31.0
 semver==2.8.1

libbeat/tests/system/requirements_aix.txt

@@ -35,7 +35,7 @@ pyrsistent==0.16.0
 pytest==7.3.2
 pytest-rerunfailures==9.1.1
 pytest-timeout==1.4.2
-PyYAML==5.4.1
+PyYAML==5.3.1
 redis==4.4.4
 requests==2.31.0
 semver==2.8.1

metricbeat/Dockerfile

@@ -21,7 +21,7 @@ ENV PATH="$VIRTUAL_ENV/bin:$PATH"
 RUN pip3 install --upgrade pip==20.1.1
 RUN pip3 install --upgrade docker-compose==1.23.2
 RUN pip3 install --upgrade setuptools==47.3.2
-RUN pip3 install --upgrade PyYAML==6.0.0
+RUN pip3 install --upgrade PyYAML==5.3.1
 
 # Oracle instant client
 RUN cd /usr/lib \

metricbeat/module/kubernetes/_meta/terraform/eks/requirements.txt

@@ -5,7 +5,7 @@ docutils==0.15.2
 jmespath==0.9.5
 pyasn1==0.4.8
 python-dateutil==2.8.1
-PyYAML==5.4.1
+PyYAML==5.3.1
 rsa==4.7.2
 s3transfer==0.3.3
 six==1.14.0