conan: Fix build

conan has very strict requirements on the versions of its dependencies.
This patch adds downgraded versinos of node-semver and distro to
statisfy these requirements.

pkgs/development/python-modules/node-semver/2.nix

@@ -0,0 +1,21 @@
+{ stdenv, fetchPypi, buildPythonPackage, pytest, tox }:
+
+buildPythonPackage rec {
+  name = "${pname}-${version}";
+  version = "0.2.0";
+  pname = "node-semver";
+
+  buildInputs = [ pytest tox ];
+
+  src = fetchPypi {
+    inherit pname version;
+    sha256 = "1080pdxrvnkr8i7b7bk0dfx6cwrkkzzfaranl7207q6rdybzqay3";
+  };
+
+  meta = with stdenv.lib; {
+    homepage = https://github.com/podhmo/python-semver;
+    description = "A port of node-semver";
+    license = licenses.mit;
+    platforms = platforms.all;
+  };
+}