Update Ember dependencies

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
ember-cli (source)	devDependencies	minor	3.20.0 -> 3.21.0
ember-source (source)	devDependencies	minor	3.20.4 -> 3.21.1

---

Release Notes

ember-cli/ember-cli

v3.21.0

Compare Source

Blueprint Changes

• ember new diff
• ember addon diff

Changelog

• #​9305 Update blueprint dependencies to latest versions. @​rwjblue
• #​9306 Ensure that outputReady receives the final output directory. @​rwjblue
• #​9308 Add Ember 3.20 LTS to ember-try configuration. @​rwjblue
• #​9309 Update blueprint dependencies to latest @​rwjblue
• #​9310 Drop Ember 3.12 from default addon testing matrix. @​rwjblue
• #​9259 Implement emberjs/rfcs#​635: ember new --lang @​josephdsumner
• #​9299 Remove explicit yarn install in blueprint generated .travis.yml (use the Travis CI default of yarn install --frozen-lockfile) @​kellyselden
• #​9289 Update blueprint dependencies / devDependencies @​rwjblue

v3.20.1

Compare Source

Blueprint Changes

• ember new diff
• ember addon diff

Changelog

• #​9308 Add Ember 3.20 LTS to ember-try configuration. @​rwjblue

Thank you to all who took the time to contribute!

emberjs/ember.js

v3.21.1

Compare Source

• #​19106 [BUGFIX] Ensure destroy methods on CoreObject are invoked.
• #​19111 [BUGFIX] Fixes ArrayProxy length reactivity.

v3.21.0

Compare Source

• #​18993 [DEPRECATION] Deprecate getWithDefault per RFC #​554.
• #​19087 [BUGFIX] Generated initializer tests no longer causes a deprecation warning
• #​17571 [BUGFIX] Avoid tampering queryParam argument in RouterService#isActive

v3.20.5

Compare Source

• #​19106 [BUGFIX] Ensure destroy methods on CoreObject are invoked.
• #​19111 [BUGFIX] Fixes ArrayProxy length reactivity.

---

Renovate configuration

📅 Schedule: "before 3am on Monday" (UTC).

🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.

♻️ Rebasing: Renovate will not automatically rebase this PR, because other commits have been found.

👻 Immortal: This PR will be recreated if closed unmerged. Get config help if that's undesired.

---

• If you want to rebase/retry this PR, check this box

---

This PR has been generated by WhiteSource Renovate. View repository job log here.