add Duckduckgo pkg (#1392)

### What problem does this PR solve?

#918 

### Type of change

- [x] Documentation Update

requirements.txt

@@ -143,4 +143,5 @@ webdriver-manager==4.0.1
 cn2an==0.5.22
 roman-numbers==1.0.2
 word2number==1.1
-markdown==3.6
+markdown==3.6
+duckduckgo_search==6.1.9

requirements_arm.txt

@@ -145,3 +145,4 @@ cn2an==0.5.22
 roman-numbers==1.0.2
 word2number==1.1
 markdown==3.6
+duckduckgo_search==6.1.9

requirements_dev.txt

@@ -130,3 +130,4 @@ cn2an==0.5.22
 roman-numbers==1.0.2
 word2number==1.1
 markdown==3.6
+duckduckgo_search==6.1.9