Bump go1.26 and referenced package versions

[BergCyrill]

The osv-scanner detected the following (possible) vulnerabilities.
We should bump the used go version during compilation as well as some package dependencies.

+------------------------------+------+-----------+-------------------+---------+---------------+--------+
| OSV URL | CVSS | ECOSYSTEM | PACKAGE | VERSION | FIXED VERSION | SOURCE |
+------------------------------+------+-----------+-------------------+---------+---------------+--------+
| https://osv.dev/GO-2026-6179 | | Go | golang.org/x/mod | 0.35.0 | 0.40.0 | go.mod |
| https://osv.dev/GO-2026-6180 | | Go | golang.org/x/mod | 0.35.0 | 0.40.0 | go.mod |
| https://osv.dev/GO-2026-5942 | | Go | golang.org/x/net | 0.55.0 | 0.56.0 | go.mod |
| https://osv.dev/GO-2026-5970 | | Go | golang.org/x/text | 0.37.0 | 0.39.0 | go.mod |
| https://osv.dev/GO-2026-5026 | | Go | stdlib | 1.26.5 | 1.26.6 | go.mod |
| https://osv.dev/GO-2026-5942 | | Go | stdlib | 1.26.5 | 1.26.6 | go.mod |
| https://osv.dev/GO-2026-5972 | | Go | stdlib | 1.26.5 | 1.26.6 | go.mod |
| https://osv.dev/GO-2026-6088 | | Go | stdlib | 1.26.5 | 1.26.6 | go.mod |
| https://osv.dev/GO-2026-6089 | | Go | stdlib | 1.26.5 | 1.26.6 | go.mod |
| https://osv.dev/GO-2026-6090 | | Go | stdlib | 1.26.5 | 1.26.6 | go.mod |
| https://osv.dev/GO-2026-6091 | | Go | stdlib | 1.26.5 | 1.26.6 | go.mod |
| https://osv.dev/GO-2026-6218 | | Go | stdlib | 1.26.5 | 1.26.6 | go.mod |
+------------------------------+------+-----------+-------------------+---------+---------------+--------+