Fix ruby alpine CI template

COPY Gemfile Gemfile.lock . is invalid syntax.
When using COPY with more than one source file,
the destination must be a directory and end with a /
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

changelogs/unreleased/dz-fix-ruby-alpine-template.yml

+---
+title: Fix ruby alpine CI template
+merge_request: 57109
+author:
+type: fixed

vendor/Dockerfile/Ruby-alpine.Dockerfile

@@ -9,7 +9,7 @@ RUN bundle config --global frozen 1
 
 WORKDIR /usr/src/app
 
-COPY Gemfile Gemfile.lock .
+COPY Gemfile Gemfile.lock /usr/src/app/
 # Install build dependencies - required for gems with native dependencies
 RUN apk add --no-cache --virtual build-deps build-base postgresql-dev && \
   bundle install && \