Update requirements.txt

1. The operator '==' caused certain packages to downgrade if a newer version was already installed on the target PC.
Therefore, I think that '>=' would be more appropriate instead of '=='.

2. Deleted a redundant new line (Line 18).

requirements.txt

@@ -1,17 +1,17 @@
-beautifulsoup4==4.7.1
-bs4==0.0.1
-cached-property==1.5.1
-certifi==2019.6.16
-chardet==3.0.4
-commonmark==0.9.0
-dictdiffer==0.8.0
-future==0.17.1
-idna==2.8
-notion==0.0.23
-python-slugify==3.0.2
-pytz==2019.1
-requests==2.22.0
-soupsieve==1.9.2
-text-unidecode==1.2
-tzlocal==1.5.1
-urllib3==1.25.3
+beautifulsoup4>=4.7.1
+bs4>=0.0.1
+cached-property>=1.5.1
+certifi>=2019.6.16
+chardet>=3.0.4
+commonmark>=0.9.0
+dictdiffer>=0.8.0
+future>=0.17.1
+idna>=2.8
+notion>=0.0.23
+python-slugify>=3.0.2
+pytz>=2019.1
+requests>=2.22.0
+soupsieve>=1.9.2
+text-unidecode>=1.2
+tzlocal>=1.5.1
+urllib3>=1.25.3