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##### SUMMARY
<!--- Explain the problem briefly below -->
Hi, i am trying to read a secret from the following path
        secret: "{{ lookup('hashi_vault', 'namespace={{NAMESPACE}} secret={{ BRAND }}/{{ ENVIRONMENT }}/secrets/placeholder:foo url={{ VAULT_ADDR }} auth_method={{ VAULT_AUTH_METHOD }} role_id={{ VAULT_ROLE_ID }} secret_id={{ VAULT_SECRET_ID }}')}}"

but this fails with no secret found at location. 
we are using enterprise and this uses the KV engine

vault kv get {{ BRAND }}/{{ ENVIRONMENT }}/secrets/placeholder:foo


##### ISSUE TYPE
- Bug Report
unable to read from kv data store

##### COMPONENT NAME
<!--- Write the short name of the module, plugin, task or feature below, use your best guess if unsure -->
hashi_vault

##### ANSIBLE VERSION
<!--- Paste verbatim output from "ansible --version" between quotes -->
```paste below
2.8
```

##### CONFIGURATION
<!--- Paste verbatim output from "ansible-config dump --only-changed" between quotes -->
```paste below

```

##### OS / ENVIRONMENT
<!--- Provide all relevant information below, e.g. target OS versions, network device firmware, etc. -->


##### STEPS TO REPRODUCE
<!--- Describe exactly how to reproduce the problem, using a minimal test-case -->

<!--- Paste example playbooks or commands between quotes below -->
```yaml

```

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##### EXPECTED RESULTS
<!--- Describe what you expected to happen when running the steps above -->


##### ACTUAL RESULTS
<!--- Describe what actually happened. If possible run with extra verbosity (-vvvv) -->

<!--- Paste verbatim command output between quotes -->
```paste below

```

if self.auth_method and self.auth_method != 'token':
            try:
                if self.namespace is not None:
                    self.client = hvac.Client(url=self.url, verify=self.verify, namespace=self.namespace)
                else:
                    self.client = hvac.Client(url=self.url, verify=self.verify)
                
                getattr(self, 'auth_' + self.auth_method)(**kwargs)
            except AttributeError:
                raise AnsibleError("Authentication method '%s' not supported."
                                   " Available options are %r" % (self.auth_method, self.avail_auth_method))
        else:
            self.token = kwargs.get('token', os.environ.get('VAULT_TOKEN', None))
            if self.token is None and os.environ.get('HOME'):
                token_filename = os.path.join(
                    os.environ.get('HOME'),
                    '.vault-token'
                )
                if os.path.exists(token_filename):
                    with open(token_filename) as token_file:
                        self.token = token_file.read().strip()
            if self.token is None:
                raise AnsibleError("No Vault Token specified")
            if self.namespace is not None:
                self.client = hvac.Client(url=self.url, token=self.token, verify=self.verify, namespace=self.namespace)
            else:
                self.client = hvac.Client(url=self.url, token=self.token, verify=self.verify)
        if not self.client.is_authenticated():
            raise AnsibleError("Invalid Hashicorp Vault Token Specified for hashi_vault lookup")
    def get(self):