add english locale, fixes #4321

Closes #4321

Merge request studip/studip!3120

docker/studip/Dockerfile

@@ -12,9 +12,15 @@ RUN apt update && apt install -y --no-install-recommends \
         libzip-dev \
         libicu-dev \
         libwebp-dev \
+        locales \
         vim \
     && rm -rf /var/lib/apt/lists/*
 
+# Install locales
+RUN sed -i -e 's/# en_GB.UTF-8 UTF-8/en_GB.UTF-8 UTF-8/' /etc/locale.gen \
+    && dpkg-reconfigure --frontend=noninteractive locales \
+    && update-locale
+
 # Install php extensions
 RUN docker-php-ext-configure gd --with-jpeg --with-webp
 RUN docker-php-ext-install gettext gd zip pdo_mysql mysqli intl

docker/studip/Dockerfile-Dev

@@ -12,9 +12,15 @@ RUN apt update && apt install -y --no-install-recommends \
         libzip-dev \
         libicu-dev \
         libwebp-dev \
+        locales \
         vim \
     && rm -rf /var/lib/apt/lists/*
 
+# Install locales
+RUN sed -i -e 's/# en_GB.UTF-8 UTF-8/en_GB.UTF-8 UTF-8/' /etc/locale.gen \
+    && dpkg-reconfigure --frontend=noninteractive locales \
+    && update-locale
+
 # Install php extensions
 RUN docker-php-ext-configure gd --with-jpeg --with-webp
 RUN docker-php-ext-install pdo gettext curl gd mbstring zip pdo pdo_mysql mysqli intl json