feat: bump alpine 3.23

Dockerfile

@@ -1,11 +1,14 @@
-FROM "alpine:3.7"
+FROM "alpine:3.23"
 LABEL maintainer="Cabillot Julien <dockerimages@cabillot.eu>"
 
 COPY entrypoint.sh /entrypoint.sh
 
 RUN apk add --no-cache offlineimap openssl && \
-    adduser -D offlineimap
-COPY offlineimaprc /home/offlineimap/.offlineimaprc
+    adduser -D offlineimap && \
+    # Force SECLEVEL=1 in imaplib2 to allow connecting to servers with weak DH keys (DH_KEY_TOO_SMALL)
+    # This is required because OpenSSL 3.x in Alpine 3.23 defaults to SECLEVEL=2
+    sed -i 's/ctx = ssl.SSLContext(ssl_version)/ctx = ssl.SSLContext(ssl_version)\n                ctx.set_ciphers("DEFAULT:@SECLEVEL=1")/' /usr/lib/python3.*/site-packages/imaplib2/imaplib2.py
+COPY --chown=offlineimap offlineimaprc /home/offlineimap/.offlineimaprc
 
 # Add Tini
 #ENV "TINI_VERSION" "v0.16.1"