Fix trnaslation links of articles

In Pelican, all languages need to use the same slug

Fix trnaslation links of articles
1880a3ad · Nik | Klampfradler · 8042c77f · 1880a3ad · 1880a3ad
Verified Commit 1880a3ad authored 3 years ago by Nik | Klampfradler
--- a/content/posts/en/2021-01-16_joint-statement-concerning-cloud-software-schools.html
+++ b/content/posts/en/2021-01-16_joint-statement-concerning-cloud-software-schools.html
--- a/content/posts/en/2021-01-27_teckids-rc3.html
+++ b/content/posts/en/2021-01-27_teckids-rc3.html