Bump Npgsql from 5.0.11 to 7.0.6 (#223)

Bumps [Npgsql](https://github.com/npgsql/npgsql) from 5.0.11 to 7.0.6.
- [Release notes](https://github.com/npgsql/npgsql/releases)
- [Commits](npgsql/npgsql@v5.0.11...v7.0.6)

---
updated-dependencies:
- dependency-name: Npgsql
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

src/Directory.Build.props

@@ -19,7 +19,7 @@
     <AkkaVersion>1.5.13</AkkaVersion>
 
     <!-- Install from version 5.0.11 included all the way up to 7.x.x, but don't go up a major version -->
-    <PostgresLowVersion>5.0.11</PostgresLowVersion>
+    <PostgresLowVersion>7.0.6</PostgresLowVersion>
     <PostgresHighVersion>8</PostgresHighVersion>
     <PostgresVersion>[$(PostgresLowVersion), $(PostgresHighVersion))</PostgresVersion>
   </PropertyGroup>