fix: add maxlength

[vitormattos]

According to RFC 5280, the CN must not exceed 64 characters.

ref: https://www.rfc-editor.org/rfc/rfc5280#page-124

Related with:

• OpenSSL does not accept DNs longer than 65 characters #5479

[vitormattos]

/backport to stable32

[vitormattos]

/backport to stable31

[backportbot-libresign]

The backport to stable31 failed. Please do this backport manually.

# Switch to the target branch and update it
git checkout stable31
git pull origin stable31

# Create the new backport branch
git checkout -b backport/5540/stable31

# Cherry pick the change from the commit sha1 of the change against the default branch
# This might cause conflicts, resolve them
git cherry-pick 69b57303

# Push the cherry pick commit to the remote repository and open a pull request
git push origin backport/5540/stable31

Error: Failed to create pull request:

---

Learn more about backports at https://docs.nextcloud.com/server/stable/go.php?to=developer-backports.

[backportbot-libresign]

The backport to stable32 failed. Please do this backport manually.

# Switch to the target branch and update it
git checkout stable32
git pull origin stable32

# Create the new backport branch
git checkout -b backport/5540/stable32

# Cherry pick the change from the commit sha1 of the change against the default branch
# This might cause conflicts, resolve them
git cherry-pick 69b57303

# Push the cherry pick commit to the remote repository and open a pull request
git push origin backport/5540/stable32

Error: Failed to create pull request:

---

Learn more about backports at https://docs.nextcloud.com/server/stable/go.php?to=developer-backports.

[vitormattos]

/backport to stable31

[vitormattos]

/backport to stable32

[backportbot-libresign]

The backport to stable32 failed. Please do this backport manually.

# Switch to the target branch and update it
git checkout stable32
git pull origin stable32

# Create the new backport branch
git checkout -b backport/5540/stable32

# Cherry pick the change from the commit sha1 of the change against the default branch
# This might cause conflicts, resolve them
git cherry-pick 69b57303

# Push the cherry pick commit to the remote repository and open a pull request
git push origin backport/5540/stable32

Error: Failed to create pull request: Validation Failed: {"resource":"PullRequest","code":"custom","message":"A pull request already exists for LibreSign:backport/5540/stable32."}

---

Learn more about backports at https://docs.nextcloud.com/server/stable/go.php?to=developer-backports.

[vitormattos]

/backport to stable31