Minimal supported PIO Core is 6.0

Author: ivankravets

src/constants.js

@@ -9,7 +9,7 @@
 export const IS_WINDOWS = process.platform.startsWith('win');
 export const IS_OSX = process.platform == 'darwin';
 export const IS_LINUX = !IS_WINDOWS && !IS_OSX;
-export const PIO_CORE_VERSION_SPEC = '>=5.1';
+export const PIO_CORE_VERSION_SPEC = '>=6';
 export const STATUS_BAR_PRIORITY_START = 10;
 export const CONFLICTED_EXTENSION_IDS = [
   'llvm-vs-code-extensions.vscode-clangd',