Update module golang.org/x/mod to v0.15.0 (open-telemetry#31235)

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This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| golang.org/x/mod | `v0.14.0` -> `v0.15.0` |
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cmd/configschema/go.mod

@@ -15,7 +15,7 @@ require (
  go.opentelemetry.io/collector/otelcol v0.94.1
  go.opentelemetry.io/collector/receiver/otlpreceiver v0.94.1
  go.uber.org/goleak v1.3.0
- golang.org/x/mod v0.14.0
+ golang.org/x/mod v0.15.0
  golang.org/x/text v0.14.0
  gopkg.in/yaml.v2 v2.4.0
 )