2.6.0 release

• javascript-obfuscator now is a peerDependency
• Migration to webpack@5
• Optimized performance of ExpressionStatementsMergeTransformer when simplify option is enabled. Fixed javascript-obfuscator/javascript-obfuscator#777
• Fixed broken identifierNamesGenerator: 'mangled-shuffled' after 2.2.0. Fixed javascript-obfuscator/javascript-obfuscator#778