I don't know if this is the correct answer but when I comment out the **/.gitignore line in the .dockerignore file, I can build the docker image.

My .dockerignore file:

**/.classpath
**/.dockerignore
**/.env
**/.git
# **/.gitignore
**/.project
**/.settings
**/.toolstarget
**/.vs
**/.vscode
**/.next
**/.cache
**/*.*proj.user
**/*.dbmdl
**/*.jfm
**/charts
**/docker-compose*
**/compose*
**/Dockerfile*
**/node_modules
**/npm-debug.log
**/obj
**/secrets.dev.yaml
**/values.dev.yaml
**/build
**/dist
LICENSE
README.md
**/.angular