feat: add python 3.11.1 to the samples image (GoogleCloudPlatform#8861)

Author: parthea

.kokoro/docker/Dockerfile

@@ -117,7 +117,7 @@ RUN set -ex \
  && export GNUPGHOME="$(mktemp -d)" \
  && echo "disable-ipv6" >> "${GNUPGHOME}/dirmngr.conf" \
  && /tmp/fetch_gpg_keys.sh \
- && for PYTHON_VERSION in 2.7.18 3.7.12 3.8.13 3.9.13 3.10.5; do \
+ && for PYTHON_VERSION in 2.7.18 3.7.12 3.8.13 3.9.13 3.10.5 3.11.1; do \
  wget --no-check-certificate -O python-${PYTHON_VERSION}.tar.xz "https://www.python.org/ftp/python/${PYTHON_VERSION%%[a-z]*}/Python-$PYTHON_VERSION.tar.xz" \
  && wget --no-check-certificate -O python-${PYTHON_VERSION}.tar.xz.asc "https://www.python.org/ftp/python/${PYTHON_VERSION%%[a-z]*}/Python-$PYTHON_VERSION.tar.xz.asc" \
  && gpg --batch --verify python-${PYTHON_VERSION}.tar.xz.asc python-${PYTHON_VERSION}.tar.xz \
@@ -157,6 +157,7 @@ RUN wget --no-check-certificate -O /tmp/get-pip.py 'https://bootstrap.pypa.io/ge
  && [ "$(pip list |tac|tac| awk -F '[ ()]+' '$1 == "pip" { print $2; exit }')" = "$PYTHON_PIP_VERSION" ]
 
 # Ensure Pip for all python3 versions
+RUN python3.11 /tmp/get-pip.py
 RUN python3.9 /tmp/get-pip.py
 RUN python3.8 /tmp/get-pip.py
 RUN python3.7 /tmp/get-pip.py
@@ -168,6 +169,7 @@ RUN python3.7 -m pip
 RUN python3.8 -m pip
 RUN python3.9 -m pip
 RUN python3.10 -m pip
+RUN python3.11 -m pip
 
 # Install "virtualenv", since the vast majority of users of this image
 # will want it.