fix: make accessMode configurable via values.yaml

[blackbass64]

Description of the change

This PR updates the pvc.yaml to support dynamic input for accessMode from the values.yaml file. Previously, the access mode was hard-coded as ReadWriteOnce. With this change, users can configure the accessMode via values.yaml.

Benefits

• Increased flexibility in specifying Persistent Volume access modes.
• Allows users to configure different accessMode options like ReadWriteMany, ReadOnlyMany, etc., depending on their use case.

Possible drawbacks

• Users who don't specify the accessMode or leave the value as null in values.yaml will default to ReadWriteOnce, which may not fit every scenario.

Applicable issues

• fixes #

Additional information

No breaking changes are introduced, and this only extends the functionality by making the accessMode configurable.

Checklist

• Chart version bumped in Chart.yaml according to semver.
• Variables are documented in the README.md