F deprecate yamlapi

Summary

The yamlapi should be obsolete in future (see Issue #62 (closed)). Warnings to all functions of this API were added.

Focus

All changes were made in the yamlapi. Tests for the warning were added.

Test Environment

tox

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src/caosdb/yamlapi.py

@@ -102,7+102,7 @@
 
 
 def process(text):
     """Do some replacements on the original file to obtain valid yaml."""
     warnings.warn("""
                   This function is deprecated and will be removed with the next release.
                   Please use caosdb-advanced-user-tools/models/data_model.py for a
@@ -137,7+137,7 @@
                   This function is deprecated and will be removed with the next release.
                   Please use caosdb-advanced-user-tools/models/data_model.py for a
                   similar functionality.""", DeprecationWarning)
+    con = get_connection()
     prs = etree.XMLParser(remove_blank_text=True)
     sent_xml = etree.tostring(
         etree.fromstring(