Read OpenCV version info from config object in package.json. This way we're compatible across npm@6 and npm@7

Author: s1hofmann

install/dependencies.js

@@ -21,18 +21,9 @@ if (!process.env["OPENCV4NODEJS_PREBUILT_SKIP_DEPENDENCIES"]) {
     }
 
     const op = process.platform;
-    let openCvVersion =  process.env.npm_package_opencv;
 
-    if (!openCvVersion) {
-        // npm 7 no longer sets fields from the package.json in process.env so lookup the package.json
-        // file we're running from. The environment variables are different when running locally vs
-        // as a dependency
-        const package = require(process.env.npm_package_from || process.env.npm_package_json);
-        openCvVersion = package.opencv;
-    }
-
-    console.log(`Installing prebuilt OpenCV v${openCvVersion} for platform ${op}`);
-    install(`@nut-tree/opencv-build-${op}@${openCvVersion}`);
+    console.log(`Installing prebuilt OpenCV v${process.env.npm_package_config_opencv} for plattform ${op}`);
+    install(`@nut-tree/opencv-build-${op}@${process.env.npm_package_config_opencv}`);
     packages[op].forEach(pkg => {
         console.log(`Installing additional runtime dependency '${pkg}'`);
         install(pkg);