fixed bug with update-version.sh

[rockhowse]

This addresses a bug in the update-versions.sh script to tighten the regular expression to limit the main -> release/YY.MM pattern so it's limited to only the cuvs URL in the SPDX header section.

• no non-cuvs SPDX headers are modified
• all other references to main in the python/cuvs_bench/cuvs_bench/plot/__main__.py file should no longer be modified

In theory this should forward merge and NOT be reverted as it:

• fixes the update-versions.sh script to have limited regex
• reverts the non-cuvs urls to use main instead of release/25.12 <-- will be a no-op in main?

[rockhowse]

If we set the file back to what should exist in main:

diff --git a/python/cuvs_bench/cuvs_bench/plot/__main__.py b/python/cuvs_bench/cuvs_bench/plot/__main__.py
index 15c98a44..683fe659 100644
--- a/python/cuvs_bench/cuvs_bench/plot/__main__.py
+++ b/python/cuvs_bench/cuvs_bench/plot/__main__.py
@@ -6,7 +6,7 @@
 # 1: https://github.com/erikbern/ann-benchmarks/blob/release/main/plot.py
 # 2: https://github.com/erikbern/ann-benchmarks/blob/release/main/ann_benchmarks/plotting/utils.py  # noqa: E501
 # 3: https://github.com/erikbern/ann-benchmarks/blob/release/main/ann_benchmarks/plotting/metrics.py  # noqa: E501
-# License: https://github.com/rapidsai/cuvs/blob/release/25.12/thirdparty/LICENSES/LICENSE.ann-benchmark # noqa: E501
+# License: https://github.com/rapidsai/cuvs/blob/main/thirdparty/LICENSES/LICENSE.ann-benchmark # noqa: E501

And re-run the update-version.sh in release mode with version 25.12, the only line that gets updated to release/25.12 is the expected rapidsai/cuvs line in the SPDX header section

>./ci/release/update-version.sh --run-context=release 25.12.00 
Using run-context from CLI: release
Preparing release branch update 25.12.00a => 25.12.00 (targeting release/25.12 branch)

> git diff 
<no differences>