package/go: bump to 1.15.4

Bugfix release. From the release notes:

go1.15.4 (released 2020/11/05) includes fixes to cgo, the compiler, linker,
runtime, and the compress/flate, net/http, reflect, and time packages.

Signed-off-by: Christian Stewart <christian@paral.in>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/go/go.hash

@@ -1,4 +1,3 @@
 # From https://golang.org/dl/
-sha256	28bf9d0bcde251011caae230a4a05d917b172ea203f2a62f2c2f9533589d4b4d  go1.15.2.src.tar.gz
-sha256	896a602570e54c8cdfc2c1348abd4ffd1016758d0bd086ccd9787dbfc9b64888  go1.15.3.src.tar.gz
+sha256  063da6a9a4186b8118a0e584532c8c94e65582e2cd951ed078bfd595d27d2367  go1.15.4.src.tar.gz
 sha256	2d36597f7117c38b006835ae7f537487207d8ec407aa9d9980794b2030cbc067  LICENSE

package/go/go.mk

@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-GO_VERSION = 1.15.3
+GO_VERSION = 1.15.4
 GO_SITE = https://storage.googleapis.com/golang
 GO_SOURCE = go$(GO_VERSION).src.tar.gz