Bump gopkg.in/DataDog/dd-trace-go.v1 in /exporter/datadogexporter (#1915

)

Bumps [gopkg.in/DataDog/dd-trace-go.v1](https://github.com/DataDog/dd-trace-go) from 1.27.1 to 1.28.0.
- [Release notes](https://github.com/DataDog/dd-trace-go/releases)
- [Commits](DataDog/dd-trace-go@v1.27.1...v1.28.0)

Signed-off-by: dependabot[bot] <support@github.com>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

exporter/datadogexporter/go.mod

@@ -11,6 +11,6 @@ require (
 	github.com/zorkian/go-datadog-api v2.29.0+incompatible // indirect
 	go.opentelemetry.io/collector v0.17.0
 	go.uber.org/zap v1.16.0
-	gopkg.in/DataDog/dd-trace-go.v1 v1.27.1
+	gopkg.in/DataDog/dd-trace-go.v1 v1.28.0
 	gopkg.in/zorkian/go-datadog-api.v2 v2.30.0
 )

exporter/datadogexporter/go.sum

@@ -1414,8 +1414,8 @@ google.golang.org/protobuf v1.23.1-0.20200526195155-81db48ad09cc/go.mod h1:EGpAD
 google.golang.org/protobuf v1.24.0/go.mod h1:r/3tXBNzIEhYS9I1OUVjXDlt8tc493IdKGjtUeSXeh4=
 google.golang.org/protobuf v1.25.0 h1:Ejskq+SyPohKW+1uil0JJMtmHCgJPJ/qWTxr8qp+R4c=
 google.golang.org/protobuf v1.25.0/go.mod h1:9JNX74DMeImyA3h4bdi1ymwjUzf21/xIlbajtzgsN7c=
-gopkg.in/DataDog/dd-trace-go.v1 v1.27.1 h1:9BJfwtuCUrUiNB3WCTXHuaP5E/J/zfMPUUaRJoEQfdc=
-gopkg.in/DataDog/dd-trace-go.v1 v1.27.1/go.mod h1:Sp1lku8WJMvNV0kjDI4Ni/T7J/U3BO5ct5kEaoVU8+I=
+gopkg.in/DataDog/dd-trace-go.v1 v1.28.0 h1:EmglUJuykRsTwsQDcKaAo3CmOunWU6Dqk7U2lo7Pjss=
+gopkg.in/DataDog/dd-trace-go.v1 v1.28.0/go.mod h1:Sp1lku8WJMvNV0kjDI4Ni/T7J/U3BO5ct5kEaoVU8+I=
 gopkg.in/alecthomas/kingpin.v2 v2.2.6/go.mod h1:FMv+mEhP44yOT+4EoQTLFTRgOQ1FBLkstjWtayDeSgw=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=