chore(deps): update alpine docker tag to v3.20

| datasource | package | from | to   |
| ---------- | ------- | ---- | ---- |
| docker     | alpine  | 3.19 | 3.20 |

linux/Dockerfile

@@ -1,7 +1,7 @@
 # renovate: datasource=github-releases depName=watchtower lookupName=containrrr/watchtower
 ARG WATCHTOWER_VERSION=1.7.1
 
-FROM alpine:3.19@sha256:c5b1261d6d3e43071626931fc004f70149baeba2c8ec672bd4f27761f8e1ad6b as base
+FROM alpine:3.20@sha256:8768f0ca8ce33ec230c116364fbaebc1e18aaabbbda1ced56658f5eb0012202b as base
 
 #=================
 # build