upgpkg: 0.21.0-2 - use SOURCE_DATE_EPOCH for embedded build timestamp

.SRCINFO

 pkgbase = popeye
 	pkgdesc = Kubernetes cluster resource sanitizer
 	pkgver = 0.21.0
-	pkgrel = 1
+	pkgrel = 2
 	url = https://github.com/derailed/popeye
 	arch = x86_64
 	license = Apache

PKGBUILD

@@ -2,7 +2,7 @@
 
 pkgname=popeye
 pkgver=0.21.0
-pkgrel=1
+pkgrel=2
 pkgdesc="Kubernetes cluster resource sanitizer"
 arch=('x86_64')
 url="https://github.com/derailed/popeye"
@@ -23,7 +23,7 @@ build(){
   export GOFLAGS="-buildmode=pie -trimpath -mod=readonly -modcacherw"
 
   go build -v -x \
-    -ldflags "-linkmode external -w -X github.com/derailed/popeye/cmd.version=${pkgver} -X github.com/derailed/popeye/cmd.date=$(date +%FT%T%Z)"\
+    -ldflags "-linkmode external -w -X github.com/derailed/popeye/cmd.version=${pkgver} -X github.com/derailed/popeye/cmd.date=$(date -ud "@${SOURCE_DATE_EPOCH}" +%FT%T%Z)"\
     .
 }