install-poetry.py: Use for 1.1.7 and up

See also:
- https://github.com/python-poetry/poetry/releases/tag/1.1.7
- asdf-community#10 (comment)

bin/install

@@ -31,7 +31,7 @@ install_poetry() {
  fail "asdf-poetry supports release installs only"
  fi
 
- semver_ge "$ASDF_INSTALL_VERSION" 1.2.0 && vercomp="ge" || vercomp="lt"
+ semver_ge "$ASDF_INSTALL_VERSION" 1.1.7 && vercomp="ge" || vercomp="lt"
 
  if [ $vercomp == "ge" ]; then
  install_url="https://raw.githubusercontent.com/python-poetry/poetry/master/install-poetry.py"