Upgrade and Modernize

[svan-jansson]

This PR modernizes the project’s build, CI, and test setup while upgrading both the Elixir and .NET dependency stacks for the SQL Server driver (Netler-backed .NET worker + DBConnection protocol).

Changes:

• Test for all Microsoft-supported versions of MS Sql Server
• Replace hardcoded SQL Server test connection strings with a Testcontainers-provisioned container started in test/test_helper.exs.
• Upgrade the .NET worker to .NET 8 + Microsoft.Data.SqlClient, and update Netler integration (including a custom Mix compiler task).
• Add benchmarking + a new GitHub Actions workflow for build/test/release automation.

[Copilot]

Pull request overview

This PR modernizes the project’s build, CI, and test setup while upgrading both the Elixir and .NET dependency stacks for the SQL Server driver (Netler-backed .NET worker + DBConnection protocol).

Changes:

• Replace hardcoded SQL Server test connection strings with a Testcontainers-provisioned container started in test/test_helper.exs.
• Upgrade the .NET worker to .NET 8 + Microsoft.Data.SqlClient, and update Netler integration (including a custom Mix compiler task).
• Add benchmarking + a new GitHub Actions workflow for build/test/release automation.

Reviewed changes

Copilot reviewed 20 out of 21 changed files in this pull request and generated 10 comments.

Show a summary per file

File	Description
test/transaction_test.exs	Switches tests to use shared connection string from app env.
test/query_test.exs	Switches tests to use shared connection string from app env.
test/prepared_statement_test.exs	Switches tests to use shared connection string from app env.
test/data_type_test.exs	Switches tests to use shared connection string from app env.
test/test_helper.exs	Starts SQL Server container via Testcontainers and publishes connection string.
mix.exs	Updates project versioning/build compilers and adds/updates dependencies (Netler/Testcontainers/Benchee/etc.).
mix.lock	Locks upgraded dependency set.
mise.toml	Pins toolchain versions for Erlang/Elixir/.NET via mise.
lib/mix/tasks/compile/dotnet_build.ex	Adds custom Mix compiler to build .NET worker reliably with Netler 0.4.x.
lib/ex_sql_client/protocol.ex	Refines DBConnection protocol behaviors (connect error handling, cursor errors, status, etc.).
dotnet/dotnet_sql_client/SqlAdapter.cs	Migrates to Microsoft.Data.SqlClient, typed RPC surface, and improved parameter handling.
dotnet/dotnet_sql_client/Program.cs	Updates Netler.NET server bootstrap to typed routes (+ logger, NoOp route).
dotnet/dotnet_sql_client/ElixirLogger.cs	Adds stderr logger to surface .NET logs in Elixir console/CI.
dotnet/dotnet_sql_client/DotnetSqlClient.csproj	Upgrades to net8.0 and updates package references.
docker-compose.yml	Removes docker-compose-based SQL Server test setup.
bench/benchmarks.exs	Adds benchmarks for query/transaction/prepared-statement + raw IPC overhead.
VERSION	Adds base version file used by release workflow.
AGENTS.md	Adds contributor/agent guidance and repository documentation.
.travis.yml	Removes Travis CI configuration.
.testcontainers.properties	Disables Ryuk for rootless Podman compatibility.
.github/workflows/build-test-publish.yml	Adds GitHub Actions pipeline for matrix testing + benchmarking + publishing.

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