Merge bitcoin/bitcoin#21662: build: update Boost download URL

36c10b9 build,boost: update download url. (fdov)

Pull request description:

  - bintray is closing.
      - updated to jfrog.io.

  For reference:
  boostorg/boost#502

ACKs for top commit:
  Sjors:
    ACK 36c10b9
  hebasto:
    ACK 36c10b9

Tree-SHA512: 6746781296c3f395a2824750cf1a578ef9a2d6b8d5c4da196a8da5d084aea01f7f2583b41b2aade7bb94dd02be71efcfd6edf7491a1a25f2d36240b18322a68e

Author: MarcoFalke

depends/packages/boost.mk

@@ -1,6 +1,6 @@
 package=boost
 $(package)_version=1_71_0
-$(package)_download_path=https://dl.bintray.com/boostorg/release/$(subst _,.,$($(package)_version))/source/
+$(package)_download_path=https://boostorg.jfrog.io/artifactory/main/release/$(subst _,.,$($(package)_version))/source/
 $(package)_file_name=boost_$($(package)_version).tar.bz2
 $(package)_sha256_hash=d73a8da01e8bf8c7eda40b4c84915071a8c8a0df4a6734537ddde4a8580524ee
 $(package)_dependencies=native_b2