Fix .copier-answers.yml template file extension to .jinja

Author: jpvelez

template/.copier-answers.yml.tmpl template/.copier-answers.yml.jinjatemplate/.copier-answers.yml.tmpl renamed to template/.copier-answers.yml.jinja

@@ -6,6 +6,7 @@
     "ghcr.io/devcontainers/features/python:1": { "version": "os-provided" }{% endif %}{% if r_data_science  %},
     "ghcr.io/rocker-org/devcontainer-features/r-apt:0.5.0": {
       "version": "4.4.3",
+      "installREnv": "true",
       "installRMarkdown": "true",
       "vscodeRSupport": "full",
       "installVscDebugger": "true",