Bump go.opentelemetry.io/otel/sdk from 1.20.0 to 1.21.0 in /example

Bumps [go.opentelemetry.io/otel/sdk](https://github.com/open-telemetry/opentelemetry-go) from 1.20.0 to 1.21.0.
- [Release notes](https://github.com/open-telemetry/opentelemetry-go/releases)
- [Changelog](https://github.com/open-telemetry/opentelemetry-go/blob/main/CHANGELOG.md)
- [Commits](open-telemetry/opentelemetry-go@v1.20.0...v1.21.0)

---
updated-dependencies:
- dependency-name: go.opentelemetry.io/otel/sdk
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

example/go.mod

@@ -4,9 +4,9 @@ go 1.19
 
 require (
 	github.com/MrAlias/flow v0.1.1
-	go.opentelemetry.io/otel v1.20.0
+	go.opentelemetry.io/otel v1.21.0
 	go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc v1.20.0
-	go.opentelemetry.io/otel/sdk v1.20.0
+	go.opentelemetry.io/otel/sdk v1.21.0
 )
 
 require (
@@ -23,8 +23,8 @@ require (
 	github.com/prometheus/common v0.44.0 // indirect
 	github.com/prometheus/procfs v0.11.1 // indirect
 	go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.20.0 // indirect
-	go.opentelemetry.io/otel/metric v1.20.0 // indirect
-	go.opentelemetry.io/otel/trace v1.20.0 // indirect
+	go.opentelemetry.io/otel/metric v1.21.0 // indirect
+	go.opentelemetry.io/otel/trace v1.21.0 // indirect
 	go.opentelemetry.io/proto/otlp v1.0.0 // indirect
 	golang.org/x/net v0.17.0 // indirect
 	golang.org/x/sys v0.14.0 // indirect

example/go.sum

@@ -31,18 +31,18 @@ github.com/prometheus/common v0.44.0/go.mod h1:ofAIvZbQ1e/nugmZGz4/qCb9Ap1VoSTIO
 github.com/prometheus/procfs v0.11.1 h1:xRC8Iq1yyca5ypa9n1EZnWZkt7dwcoRPQwX/5gwaUuI=
 github.com/prometheus/procfs v0.11.1/go.mod h1:eesXgaPo1q7lBpVMoMy0ZOFTth9hBn4W/y0/p/ScXhY=
 github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
-go.opentelemetry.io/otel v1.20.0 h1:vsb/ggIY+hUjD/zCAQHpzTmndPqv/ml2ArbsbfBYTAc=
-go.opentelemetry.io/otel v1.20.0/go.mod h1:oUIGj3D77RwJdM6PPZImDpSZGDvkD9fhesHny69JFrs=
+go.opentelemetry.io/otel v1.21.0 h1:hzLeKBZEL7Okw2mGzZ0cc4k/A7Fta0uoPgaJCr8fsFc=
+go.opentelemetry.io/otel v1.21.0/go.mod h1:QZzNPQPm1zLX4gZK4cMi+71eaorMSGT3A4znnUvNNEo=
 go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.20.0 h1:DeFD0VgTZ+Cj6hxravYYZE2W4GlneVH81iAOPjZkzk8=
 go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.20.0/go.mod h1:GijYcYmNpX1KazD5JmWGsi4P7dDTTTnfv1UbGn84MnU=
 go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc v1.20.0 h1:gvmNvqrPYovvyRmCSygkUDyL8lC5Tl845MLEwqpxhEU=
 go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc v1.20.0/go.mod h1:vNUq47TGFioo+ffTSnKNdob241vePmtNZnAODKapKd0=
-go.opentelemetry.io/otel/metric v1.20.0 h1:ZlrO8Hu9+GAhnepmRGhSU7/VkpjrNowxRN9GyKR4wzA=
-go.opentelemetry.io/otel/metric v1.20.0/go.mod h1:90DRw3nfK4D7Sm/75yQ00gTJxtkBxX+wu6YaNymbpVM=
-go.opentelemetry.io/otel/sdk v1.20.0 h1:5Jf6imeFZlZtKv9Qbo6qt2ZkmWtdWx/wzcCbNUlAWGM=
-go.opentelemetry.io/otel/sdk v1.20.0/go.mod h1:rmkSx1cZCm/tn16iWDn1GQbLtsW/LvsdEEFzCSRM6V0=
-go.opentelemetry.io/otel/trace v1.20.0 h1:+yxVAPZPbQhbC3OfAkeIVTky6iTFpcr4SiY9om7mXSQ=
-go.opentelemetry.io/otel/trace v1.20.0/go.mod h1:HJSK7F/hA5RlzpZ0zKDCHCDHm556LCDtKaAo6JmBFUU=
+go.opentelemetry.io/otel/metric v1.21.0 h1:tlYWfeo+Bocx5kLEloTjbcDwBuELRrIFxwdQ36PlJu4=
+go.opentelemetry.io/otel/metric v1.21.0/go.mod h1:o1p3CA8nNHW8j5yuQLdc1eeqEaPfzug24uvsyIEJRWM=
+go.opentelemetry.io/otel/sdk v1.21.0 h1:FTt8qirL1EysG6sTQRZ5TokkU8d0ugCj8htOgThZXQ8=
+go.opentelemetry.io/otel/sdk v1.21.0/go.mod h1:Nna6Yv7PWTdgJHVRD9hIYywQBRx7pbox6nwBnZIxl/E=
+go.opentelemetry.io/otel/trace v1.21.0 h1:WD9i5gzvoUPuXIXH24ZNBudiarZDKuekPqi/E8fpfLc=
+go.opentelemetry.io/otel/trace v1.21.0/go.mod h1:LGbsEB0f9LGjN+OZaQQ26sohbOmiMR+BaslueVtS/qQ=
 go.opentelemetry.io/proto/otlp v1.0.0 h1:T0TX0tmXU8a3CbNXzEKGeU5mIVOdf0oykP+u2lIVU/I=
 go.opentelemetry.io/proto/otlp v1.0.0/go.mod h1:Sy6pihPLfYHkr3NkUbEhGHFhINUSI/v80hjKIs5JXpM=
 go.uber.org/goleak v1.3.0 h1:2K3zAYmnTNqV73imy9J1T3WC+gmCePx2hEGkimedGto=