Removed pg14, Added pg17, bump alpine, move to matrix

Dockerfile.pg15

@@ -1,23 +1,12 @@
-FROM alpine:3.20
+FROM alpine:3.21
 
-ENV HOME=/home/app \
-    APP_HOME=/home/app/docker-postgres-backup \
-    \
-    # python
-    PYTHONPATH=${PYTHONPATH}:${PWD} \
+ENV APP_HOME=/home/app/docker-postgres-backup \
     PYTHONUNBUFFERED=1 \
     PYTHONDONTWRITEBYTECODE=1 \
     PIP_BREAK_SYSTEM_PACKAGES=1 \
-    \
-    # pip
     PIP_NO_CACHE_DIR=off \
     PIP_DISABLE_PIP_VERSION_CHECK=on \
-    PIP_DEFAULT_TIMEOUT=100 \
-    \
-    # language locales
-    LANG=en_US.UTF-8 \
-    LANGUAGE=en_US:en \
-    LC_ALL=en_US.UTF-8
+    LANG=en_US.UTF-8
 
 RUN apk --no-cache add postgresql15-client python3 py3-pip tini