fix(docker): set default shell encoding

Same as microsoft/playwright#30288

Author: campersau

utils/docker/Dockerfile.jammy

@@ -4,6 +4,9 @@ ARG DEBIAN_FRONTEND=noninteractive
 ARG TZ=America/Los_Angeles
 ARG DOCKER_IMAGE_NAME_TEMPLATE="mcr.microsoft.com/playwright/python:v%version%-jammy"
 
+ENV LANG=C.UTF-8
+ENV LC_ALL=C.UTF-8
+
 # === INSTALL Python ===
 
 RUN apt-get update && \

utils/docker/Dockerfile.noble

@@ -4,6 +4,9 @@ ARG DEBIAN_FRONTEND=noninteractive
 ARG TZ=America/Los_Angeles
 ARG DOCKER_IMAGE_NAME_TEMPLATE="mcr.microsoft.com/playwright/python:v%version%-noble"
 
+ENV LANG=C.UTF-8
+ENV LC_ALL=C.UTF-8
+
 # === INSTALL Python ===
 
 RUN apt-get update && \