build: upgrade to Go 1.15.6 (#21986)

build/checksums.txt

 # This file contains sha256 checksums of optional build dependencies.
 
-c1076b90cf94b73ebed62a81d802cd84d43d02dea8c07abdc922c57a071c84f1  go1.15.5.src.tar.gz
-359a4334b8c8f5e3067e5a76f16419791ac3fef4613d8e8e1eac0b9719915f6d  go1.15.5.darwin-amd64.tar.gz
-4c8179d406136979724c71732009c7e2e7c794dbeaaa2a043c00da34d4be0559  go1.15.5.linux-386.tar.gz
-9a58494e8da722c3aef248c9227b0e9c528c7318309827780f16220998180a0d  go1.15.5.linux-amd64.tar.gz
-a72a0b036beb4193a0214bca3fca4c5d68a38a4ccf098c909f7ce8bf08567c48  go1.15.5.linux-arm64.tar.gz
-5ea6456620d3efed5dda99238c7f23866eafdd915e5348736e631bc283c0238a  go1.15.5.linux-armv6l.tar.gz
-d812436c7e3482ba3c97172edf26afaf35aca60a5621ff4a5f6a08386505ab9c  go1.15.5.windows-386.zip
-1d24be3a200201a74be25e4134fbec467750e834e84e9c7789a9fc13248c5507  go1.15.5.windows-amd64.zip
+890bba73c5e2b19ffb1180e385ea225059eb008eb91b694875dd86ea48675817  go1.15.6.src.tar.gz
+940a73b45993a3bae5792cf324140dded34af97c548af4864d22fd6d49f3bd9f  go1.15.6.darwin-amd64.tar.gz
+ad187f02158b9a9013ef03f41d14aa69c402477f178825a3940280814bcbb755  go1.15.6.linux-386.tar.gz
+3918e6cc85e7eaaa6f859f1bdbaac772e7a825b0eb423c63d3ae68b21f84b844  go1.15.6.linux-amd64.tar.gz
+f87515b9744154ffe31182da9341d0a61eb0795551173d242c8cad209239e492  go1.15.6.linux-arm64.tar.gz
+40ba9a57764e374195018ef37c38a5fbac9bbce908eab436370631a84bfc5788  go1.15.6.linux-armv6l.tar.gz
+5872eff6746a0a5f304272b27cbe9ce186f468454e95749cce01e903fbfc0e17  go1.15.6.windows-386.zip
+b7b3808bb072c2bab73175009187fd5a7f20ffe0a31739937003a14c5c4d9006  go1.15.6.windows-amd64.zip
+9d9dd5c217c1392f1b2ed5e03e1c71bf4cf8553884e57a38e68fd37fdcfe31a8  go1.15.6.freebsd-386.tar.gz
+609f065d855aed5a0b40ef0245aacbcc0b4b7882dc3b1e75ae50576cf25265ee  go1.15.6.freebsd-amd64.tar.gz
+d4174fc217e749ac049eacc8827df879689f2246ac230d04991ae7df336f7cb2  go1.15.6.linux-ppc64le.tar.gz
+839cc6b67687d8bb7cb044e4a9a2eac0c090765cc8ec55ffe714dfb7cd51cf3a  go1.15.6.linux-s390x.tar.gz
 
 d998a84eea42f2271aca792a7b027ca5c1edfcba229e8e5a844c9ac3f336df35  golangci-lint-1.27.0-linux-armv7.tar.gz
 bf781f05b0d393b4bf0a327d9e62926949a4f14d7774d950c4e009fc766ed1d4  golangci-lint.exe-1.27.0-windows-amd64.zip

build/ci.go

@@ -152,7 +152,7 @@ var (
 	// This is the version of go that will be downloaded by
 	//
 	//     go run ci.go install -dlgo
-	dlgoVersion = "1.15.5"
+	dlgoVersion = "1.15.6"
 )
 
 var GOBIN, _ = filepath.Abs(filepath.Join("build", "bin"))