Update dependency core-js to v2.6.12

[supply-chain-sentinel]

This PR contains the following updates:

Package	Change	Age	Confidence
core-js (source)	2.6.5 → 2.6.12

---

Release Notes

zloirock/core-js (core-js)

v2.6.12

Compare Source

• Added code points / code units explicit feature detection in String#at for preventing breakage code which use obsolete String#at proposal polyfill
• Added OPEN_SOURCE_CONTRIBUTOR detection in postinstall
• Added Drone CI detection in postinstall

v2.6.11

Compare Source

• Returned usage of node -e in the postinstall scripts for better cross-platform compatibility, #​582
• Improved CI detection in the postinstall script, #​707

v2.6.10

Compare Source

• Show similar postinstall messages only once per npm i, #​597

v2.6.9

Compare Source

• Some fixes and improvements of the postinstall script like support npm color config (#​556) or adding support of ADBLOCK env variable

v2.6.8

Compare Source

• Added a workaround of a strange npx bug on postinstall, #​551

v2.6.7

Compare Source

• Added one more workaround of alternative not completely correct Symbol polyfills, #​550, #​554

v2.6.6

Compare Source

• Fixed IE8- non-enumerable properties support in Object.{ assign, entries, values }, #​541
• Fixed support of primitives in Object.getOwnPropertySymbols in Chrome 38 / 39, #​539
• Show a message on postinstall

---

Configuration

📅 Schedule: (UTC)

• Branch creation
  • At any time (no schedule defined)
• Automerge
  • At any time (no schedule defined)

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

♻ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about this update again.

---

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

---

This PR has been generated by Mend Renovate.