parse error: Invalid numeric literal at line 1, column 7

[cep21]

I have a file named pgadmin.dockerfile and it fails hadolint with

  parse error: Invalid numeric literal at line 1, column 7
  reviewdog: failed to unmarshal rdjson (DiagnosticResult): proto: syntax error (line 1:1): unexpected token 

I then rename the file from pgadmin.dockerfile to Dockerfile

diff --git a/Dockerfile b/pgadmin.dockerfile
similarity index 100%
rename from Dockerfile
rename to pgadmin.dockerfile

And the build works.