fix: check if the extension is not yaml and not yml

[kuisathaverat]

check if the extension is not yaml and not yml

Fix #731

Test

To test this pull request, you can run the following commands:

cat >EOF > pipeline.yml 
---
title: Update test values
sources:
  dummy:
    name: "Dummy"
    kind: shell
    spec:
      command: echo {{ .Value }}
targets:
  dummy:
    name: "Dummy"
    kind: shell
    spec:
      command: echo {{ .Value }}
EOF
cat <EOF > values.yml
Value: "foo"
EOF
cp pipeline.yml pipeline.yaml
cp values.yml values.yaml 
go run main.go diff --config pipeline.yml --values values.yml
go run main.go diff --config pipeline.yaml --values values.yml
go run main.go diff --config pipeline.yml --values values.yaml
go run main.go diff --config pipeline.yaml --values values.yaml

Additional Information

Tradeoff

Potential improvement

[olblak]

Oops