add specific version tag for the docker base image

Dockerfile

@@ -1,15 +1,15 @@
-FROM python:alpine
-
-WORKDIR ./
-ARG PUID=1000
-ENV GROUP dockergroup
-ENV USER docker
-ENV HOMEDIR "/home/${USER}"
-
-RUN addgroup -S "${GROUP}" && adduser -S "${USER}" -G "${GROUP}"
-USER ${USER}
-WORKDIR ${HOMEDIR}
-COPY . .
-RUN pip install --no-cache-dir -r requirements.txt
-
-CMD [ "python", "./bot.py" ]
+FROM python:3.9.12-alpine3.15
+
+WORKDIR ./
+ARG PUID=1000
+ENV GROUP dockergroup
+ENV USER docker
+ENV HOMEDIR "/home/${USER}"
+
+RUN addgroup -S "${GROUP}" && adduser -S "${USER}" -G "${GROUP}"
+USER ${USER}
+WORKDIR ${HOMEDIR}
+COPY . .
+RUN pip install --no-cache-dir -r requirements.txt
+
+CMD [ "python", "./bot.py" ]