powerShell() Windows 7 fix compatibility issues (windows)

lib/filesystem.js

@@ -195,6 +195,7 @@ function fsSize(drive, callback) {
             resolve(data);
           } else {
             exec('df -kPT 2>/dev/null', { maxBuffer: 1024 * 1024 }, (error, stdout) => {
+              // fixed issue alpine fallback
               const lines = filterLines(stdout);
               data = parseDf(lines);
               if (callback) {

lib/util.js

@@ -509,6 +509,7 @@ function powerShell(cmd) {
       process.nextTick(() => {
         try {
           const osVersion = os.release().split('.').map(Number);
+          // windows 7 compatibility issue
           const spanOptions =
             osVersion[0] < 10
               ? ['-NoProfile', '-NoLogo', '-InputFormat', 'Text', '-NoExit', '-ExecutionPolicy', 'Unrestricted', '-Command', '-']