Don't print AttributeValues in EncryptionContext.toString()

https://github.com/aws/aws-dynamodb-encryption-java/blob/master/sdk1/src/main/java/com/amazonaws/services/dynamodbv2/datamodeling/encryption/EncryptionContext.java#L220

https://github.com/aws/aws-dynamodb-encryption-java/blob/master/sdk2/src/main/java/software/amazon/cryptools/dynamodbencryptionclientsdk2/encryption/EncryptionContext.java#L182

A safe `toString()` method for `EncryptionContext` would be extremely useful for logging within material providers, and we can get there by excluding attributeValues from being printed. Since it is likely that tests rely on this today, we should consider doing this with a minor bump. (Note: We haven't published the sdk2 version yet, so it's not necessary to do a bump there.)

在链接到的 toString() 位置比较 SDK1 和 SDK2 的 EncryptionContext.java 文件，然后检查覆盖其当前字符串输出的现有测试。从记录的表示中排除 attributeValues，同时保留其余上下文，并考虑提升 SDK1 的次版本号；SDK2 尚未发布，因此无需提升 SDK2 的版本号。

由索引模型根据 Issue 内容生成。