Drop alpine 3.11, update generate-stackbrew-library.sh for alpine 3.13

Author: yosifkit

3.10-rc/alpine3.13/Dockerfile

@@ -24,7 +24,7 @@ RUN set -eux; \
 # other runtime dependencies for Python are installed later
 
 ENV GPG_KEY A035C8C19219BA821ECEA86B64E628F8D684696D
-ENV PYTHON_VERSION 3.10.0a4
+ENV PYTHON_VERSION 3.10.0a5
 
 RUN set -ex \
 	&& apk add --no-cache --virtual .fetch-deps \
@@ -114,10 +114,10 @@ RUN cd /usr/local/bin \
 	&& ln -s python3-config python-config
 
 # if this is called "PIP_VERSION", pip explodes with "ValueError: invalid truth value '<VERSION>'"
-ENV PYTHON_PIP_VERSION 20.3.3
+ENV PYTHON_PIP_VERSION 21.0.1
 # https://github.com/pypa/get-pip
-ENV PYTHON_GET_PIP_URL https://github.com/pypa/get-pip/raw/39356a9d34700a468cf847867ac1a3bd72cc5e45/get-pip.py
-ENV PYTHON_GET_PIP_SHA256 ec367c5c9b82fa13c04cfabb0a069e84496d5c36714f14d19b5f24d519d3ba25
+ENV PYTHON_GET_PIP_URL https://github.com/pypa/get-pip/raw/4be3fe44ad9dedc028629ed1497052d65d281b8e/get-pip.py
+ENV PYTHON_GET_PIP_SHA256 8006625804f55e1bd99ad4214fd07082fee27a1c35945648a58f9087a714e9d4
 
 RUN set -ex; \
 	\

3.6/alpine3.11/Dockerfile

@@ -148,10 +148,10 @@ RUN cd /usr/local/bin \
 	&& ln -s python3-config python-config
 
 # if this is called "PIP_VERSION", pip explodes with "ValueError: invalid truth value '<VERSION>'"
-ENV PYTHON_PIP_VERSION 20.3.3
+ENV PYTHON_PIP_VERSION 21.0.1
 # https://github.com/pypa/get-pip
-ENV PYTHON_GET_PIP_URL https://github.com/pypa/get-pip/raw/39356a9d34700a468cf847867ac1a3bd72cc5e45/get-pip.py
-ENV PYTHON_GET_PIP_SHA256 ec367c5c9b82fa13c04cfabb0a069e84496d5c36714f14d19b5f24d519d3ba25
+ENV PYTHON_GET_PIP_URL https://github.com/pypa/get-pip/raw/4be3fe44ad9dedc028629ed1497052d65d281b8e/get-pip.py
+ENV PYTHON_GET_PIP_SHA256 8006625804f55e1bd99ad4214fd07082fee27a1c35945648a58f9087a714e9d4
 
 RUN set -ex; \
 	\