fix: websocket is now webSocket in rxjs

[Hypercubed]

See ReactiveX/rxjs#3590

[amcdnl]

Fails build -

BUILD ERROR
packages/websocket-plugin/src/websocket-subject.ts(4,10): error TS2305: Module '"/home/circleci/workspace/app/node_modules/rxjs/websocket/index"' has no exported member 'webSocket'.

Error: packages/websocket-plugin/src/websocket-subject.ts(4,10): error TS2305: Module '"/home/circleci/workspace/app/node_modules/rxjs/websocket/index"' has no exported member 'webSocket'.

    at Object.<anonymous> (/home/circleci/workspace/app/node_modules/src/lib/ngc/compile-source-files.ts:66:62)
    at Generator.next (<anonymous>)
    at /home/circleci/workspace/app/node_modules/ng-packagr/lib/ngc/compile-source-files.js:7:71
    at new Promise (<anonymous>)
    at __awaiter (/home/circleci/workspace/app/node_modules/ng-packagr/lib/ngc/compile-source-files.js:3:12)
    at Object.compileSourceFiles (/home/circleci/workspace/app/node_modules/ng-packagr/lib/ngc/compile-source-files.js:19:12)
    at Object.<anonymous> (/home/circleci/workspace/app/node_modules/src/lib/ng-v5/entry-point/ts/compile-ngc.transform.ts:43:9)
    at Generator.next (<anonymous>)
    at /home/circleci/workspace/app/node_modules/ng-packagr/lib/ng-v5/entry-point/ts/compile-ngc.transform.js:7:71
    at new Promise (<anonymous>)

[amcdnl]

Fixed by #336

[Hypercubed]

Argh... didn't notice the yarn.lock....